diff --git a/docs/404.html b/docs/404.html
index 5bb0623..6488c03 100644
--- a/docs/404.html
+++ b/docs/404.html
@@ -9,14 +9,14 @@
   <title>404 Page not found</title>
   
    
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/horsey.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/horsey.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 <style type="text/css">
     :root #header + #content > #left > #rlblock_left {
diff --git a/docs/creating-messages/email/index.html b/docs/creating-messages/email/index.html
index a540c5d..742b997 100644
--- a/docs/creating-messages/email/index.html
+++ b/docs/creating-messages/email/index.html
@@ -12,17 +12,17 @@
     <title>Email creation :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -669,20 +669,20 @@ as fallback for the HTML version.</p>
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/creating-messages/index.html b/docs/creating-messages/index.html
index 47e5bdb..b3e6ad8 100644
--- a/docs/creating-messages/index.html
+++ b/docs/creating-messages/index.html
@@ -12,17 +12,17 @@
     <title>Creating messages :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -608,20 +608,20 @@
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/getting-started/index.html b/docs/getting-started/index.html
index d1aea3d..25c983c 100644
--- a/docs/getting-started/index.html
+++ b/docs/getting-started/index.html
@@ -12,17 +12,17 @@
     <title>Getting started :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -605,20 +605,20 @@
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/getting-started/intro/index.html b/docs/getting-started/intro/index.html
index ab297dc..880295a 100644
--- a/docs/getting-started/intro/index.html
+++ b/docs/getting-started/intro/index.html
@@ -12,17 +12,17 @@
     <title>Introduction :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -611,20 +611,20 @@ Please use <a href="https://docs.rs/lettre/0.6.2/lettre/">https://docs.rs/lettre
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/index.json b/docs/index.json
index 48f754e..fd4a344 100644
--- a/docs/index.json
+++ b/docs/index.json
@@ -32,7 +32,7 @@
     {
         "uri": "/content/sending-messages/file",
         "title": "File transport",
-        "content": "\nThe file transport writes the emails to the given directory. The name of the file will be\nmessage_id.txt.\nIt can be useful for testing purposes, or if you want to keep track of sent messages.\n\nextern crate lettre;\n\nuse std::env::temp_dir;\n\nuse lettre::file::FileEmailTransport;\nuse lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};\n\nfn main() {\n    // Write to the local temp directory\n    let mut sender = FileEmailTransport::new(temp_dir());\n    let email = SimpleSendableEmail::new(\n                    EmailAddress::new(\"user@localhost\".to_string()),\n                    vec![EmailAddress::new(\"root@localhost\".to_string())],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                );\n    \n    let result = sender.send(&email);\n    assert!(result.is_ok());\n}\n\nExample result in /tmp/b7c211bc-9811-45ce-8cd9-68eab575d695.txt:\n\nb7c211bc-9811-45ce-8cd9-68eab575d695: from=user@localhost to=root@localhost\nTo: root@localhost\nFrom: user@localhost\nSubject: Hello\nDate: Sat, 31 Oct 2015 13:42:19 +0100\nMessage-ID: b7c211bc-9811-45ce-8cd9-68eab575d695.lettre@localhost\n\nHello World!\n",
+        "content": "\nThe file transport writes the emails to the given directory. The name of the file will be\nmessage_id.txt.\nIt can be useful for testing purposes, or if you want to keep track of sent messages.\n\nextern crate lettre;\n\nuse std::env::temp_dir;\n\nuse lettre::file::FileEmailTransport;\nuse lettre::{SimpleSendableEmail, EmailTransport};\n\nfn main() {\n    // Write to the local temp directory\n    let mut sender = FileEmailTransport::new(temp_dir());\n    let email = SimpleSendableEmail::new(\n                    \"user@localhost\".to_string(),\n                    &[\"root@localhost\".to_string()],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                ).unwrap();\n    \n    let result = sender.send(&email);\n    assert!(result.is_ok());\n}\n\nExample result in /tmp/b7c211bc-9811-45ce-8cd9-68eab575d695.txt:\n\nb7c211bc-9811-45ce-8cd9-68eab575d695: from=user@localhost to=root@localhost\nTo: root@localhost\nFrom: user@localhost\nSubject: Hello\nDate: Sat, 31 Oct 2015 13:42:19 +0100\nMessage-ID: b7c211bc-9811-45ce-8cd9-68eab575d695.lettre@localhost\n\nHello World!\n",
         "tags": []
     },
     {
@@ -44,19 +44,19 @@
     {
         "uri": "/content/sending-messages/sendmail",
         "title": "Sendmail transport",
-        "content": "\nThe sendmail transport sends the email using the local sendmail command.\n\nextern crate lettre;\n\nuse lettre::sendmail::SendmailTransport;\nuse lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    EmailAddress::new(\"user@localhost\".to_string()),\n                    vec![EmailAddress::new(\"root@localhost\".to_string())],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                );\n    \n    let mut sender = SendmailTransport::new();\n    let result = sender.send(&email);\n    assert!(result.is_ok());\n}\n",
+        "content": "\nThe sendmail transport sends the email using the local sendmail command.\n\nextern crate lettre;\n\nuse lettre::sendmail::SendmailTransport;\nuse lettre::{SimpleSendableEmail, EmailTransport};\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    \"user@localhost\".to_string(),\n                    &[\"root@localhost\".to_string()],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                ).unwrap();\n    \n    let mut sender = SendmailTransport::new();\n    let result = sender.send(&email);\n    assert!(result.is_ok());\n}\n",
         "tags": []
     },
     {
         "uri": "/content/sending-messages/smtp",
         "title": "SMTP transport",
-        "content": "\nThis transport uses the SMTP protocol to send emails over the network (locally or remotely).\n\nIt is designed to be:\n\nSecured: email are encrypted by default\nModern: Unicode support for email content and sender/recipient addresses when compatible\nFast: supports tcp connection reuse\n\nThis client is designed to send emails to a relay server, and should not be used to send\nemails directly to the destination.\n\nThe relay server can be the local email server, a specific host or a third-party service.\n\nSimple example\n\nThis is the most basic example of usage:\n\nextern crate lettre;\n\nuse lettre::{SimpleSendableEmail, EmailTransport, EmailAddress, SmtpTransport};\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    EmailAddress::new(\"user@localhost\".to_string()),\n                    vec![EmailAddress::new(\"root@localhost\".to_string())],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                );\n    \n    // Open a local connection on port 25\n    let mut mailer =\n    SmtpTransport::builderunencryptedlocalhost().unwrap().build();\n    // Send the email\n    let result = mailer.send(&email);\n    \n    assert!(result.is_ok());\n}\n\n Complete example\n\nextern crate lettre;\n\nuse lettre::smtp::authentication::{Credentials, Mechanism};\nuse lettre::{SimpleSendableEmail, EmailTransport, EmailAddress, SmtpTransport};\nuse lettre::smtp::extension::ClientId;\nuse lettre::smtp::ConnectionReuseParameters;\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    EmailAddress::new(\"user@localhost\".to_string()),\n                    vec![EmailAddress::new(\"root@localhost\".to_string())],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                );\n    \n    // Connect to a remote server on a custom port\n    let mut mailer = SmtpTransport::simple_builder(\"server.tld\").unwrap()\n        // Set the name sent during EHLO/HELO, default is localhost\n        .helloname(ClientId::Domain(\"my.hostname.tld\".tostring()))\n        // Add credentials for authentication\n        .credentials(Credentials::new(\"username\".tostring(), \"password\".tostring()))\n        // Enable SMTPUTF8 if the server supports it\n        .smtp_utf8(true)\n        // Configure expected authentication mechanism\n        .authentication_mechanism(Mechanism::Plain)\n        // Enable connection reuse\n        .connection_reuse(ConnectionReuseParameters::ReuseUnlimited).build();\n    \n    let result_1 = mailer.send(&email);\n    assert!(result1.isok());\n    \n    // The second email will use the same connection\n    let result_2 = mailer.send(&email);\n    assert!(result2.isok());\n    \n    // Explicitly close the SMTP transaction as we enabled connection reuse\n    mailer.close();\n}\n\nLower level\n\nYou can also send commands, here is a simple email transaction without\nerror handling:\n\nextern crate lettre;\n\nuse lettre::EmailAddress;\nuse lettre::smtp::SMTP_PORT;\nuse lettre::smtp::client::Client;\nuse lettre::smtp::client::net::NetworkStream;\nuse lettre::smtp::extension::ClientId;\nuse lettre::smtp::commands::*;\n\nfn main() {\n    let mut email_client: ClientNetworkStream = Client::new();\n    let _ = emailclient.connect(&(\"localhost\", SMTPPORT), None);\n    let _ = emailclient.command(EhloCommand::new(ClientId::new(\"myhostname\".to_string())));\n    let _ = email_client.command(\n                MailCommand::new(Some(EmailAddress::new(\"user@example.com\".to_string())), vec![])\n            );\n    let _ = email_client.command(\n                RcptCommand::new(EmailAddress::new(\"user@example.org\".to_string()), vec![])\n            );\n    let _ = email_client.command(DataCommand);\n    let _ = emailclient.message(Box::new(\"Test email\".asbytes()));\n    let _ = email_client.command(QuitCommand);\n}\n\n",
+        "content": "\nThis transport uses the SMTP protocol to send emails over the network (locally or remotely).\n\nIt is designed to be:\n\nSecured: email are encrypted by default\nModern: Unicode support for email content and sender/recipient addresses when compatible\nFast: supports tcp connection reuse\n\nThis client is designed to send emails to a relay server, and should not be used to send\nemails directly to the destination.\n\nThe relay server can be the local email server, a specific host or a third-party service.\n\nSimple example\n\nThis is the most basic example of usage:\n\nextern crate lettre;\n\nuse lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    \"user@localhost\".to_string(),\n                    &[\"root@localhost\".to_string()],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                ).unwrap();\n    \n    // Open a local connection on port 25\n    let mut mailer =\n    SmtpTransport::builderunencryptedlocalhost().unwrap().build();\n    // Send the email\n    let result = mailer.send(&email);\n    \n    assert!(result.is_ok());\n}\n\n Complete example\n\nextern crate lettre;\n\nuse lettre::smtp::authentication::{Credentials, Mechanism};\nuse lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};\nuse lettre::smtp::extension::ClientId;\nuse lettre::smtp::ConnectionReuseParameters;\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    \"user@localhost\".to_string(),\n                    &[\"root@localhost\".to_string()],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                ).unwrap();\n    \n    // Connect to a remote server on a custom port\n    let mut mailer = SmtpTransport::simple_builder(\"server.tld\").unwrap()\n        // Set the name sent during EHLO/HELO, default is localhost\n        .helloname(ClientId::Domain(\"my.hostname.tld\".tostring()))\n        // Add credentials for authentication\n        .credentials(Credentials::new(\"username\".tostring(), \"password\".tostring()))\n        // Enable SMTPUTF8 if the server supports it\n        .smtp_utf8(true)\n        // Configure expected authentication mechanism\n        .authentication_mechanism(Mechanism::Plain)\n        // Enable connection reuse\n        .connection_reuse(ConnectionReuseParameters::ReuseUnlimited).build();\n    \n    let result_1 = mailer.send(&email);\n    assert!(result1.isok());\n    \n    // The second email will use the same connection\n    let result_2 = mailer.send(&email);\n    assert!(result2.isok());\n    \n    // Explicitly close the SMTP transaction as we enabled connection reuse\n    mailer.close();\n}\n\nLower level\n\nYou can also send commands, here is a simple email transaction without\nerror handling:\n\nextern crate lettre;\n\nuse lettre::EmailAddress;\nuse lettre::smtp::SMTP_PORT;\nuse lettre::smtp::client::Client;\nuse lettre::smtp::client::net::NetworkStream;\nuse lettre::smtp::extension::ClientId;\nuse lettre::smtp::commands::*;\n\nfn main() {\n    let mut email_client: ClientNetworkStream = Client::new();\n    let _ = emailclient.connect(&(\"localhost\", SMTPPORT), None);\n    let _ = emailclient.command(EhloCommand::new(ClientId::new(\"myhostname\".to_string())));\n    let _ = email_client.command(\n                MailCommand::new(Some(EmailAddress::new(\"user@example.com\".to_string()).unwrap()), vec![])\n            );\n    let _ = email_client.command(\n                RcptCommand::new(EmailAddress::new(\"user@example.org\".to_string()).unwrap(), vec![])\n            );\n    let _ = email_client.command(DataCommand);\n    let _ = emailclient.message(Box::new(\"Test email\".asbytes()));\n    let _ = email_client.command(QuitCommand);\n}\n\n",
         "tags": []
     },
     {
         "uri": "/content/sending-messages/stub",
         "title": "Stub transport",
-        "content": "\nThe stub transport only logs message envelope and drops the content. It can be useful for\ntesting purposes.\n\nextern crate lettre;\n\nuse lettre::stub::StubEmailTransport;\nuse lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    EmailAddress::new(\"user@localhost\".to_string()),\n                    vec![EmailAddress::new(\"root@localhost\".to_string())],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                );\n    \n    let mut sender = StubEmailTransport::new_positive();\n    let result = sender.send(&email);\n    assert!(result.is_ok());\n}\n\nWill log (when using a logger like env_logger):\n\nb7c211bc-9811-45ce-8cd9-68eab575d695: from=user@localhost to=root@localhost\n",
+        "content": "\nThe stub transport only logs message envelope and drops the content. It can be useful for\ntesting purposes.\n\nextern crate lettre;\n\nuse lettre::stub::StubEmailTransport;\nuse lettre::{SimpleSendableEmail, EmailTransport};\n\nfn main() {\n    let email = SimpleSendableEmail::new(\n                    \"user@localhost\".to_string(),\n                    &[\"root@localhost\".to_string()],\n                    \"messageid\".tostring(),\n                    \"Hello world\".to_string(),\n                ).unwrap();\n    \n    let mut sender = StubEmailTransport::new_positive();\n    let result = sender.send(&email);\n    assert!(result.is_ok());\n}\n\nWill log (when using a logger like env_logger):\n\nb7c211bc-9811-45ce-8cd9-68eab575d695: from=user@localhost to=root@localhost\n",
         "tags": []
     }
 ]
\ No newline at end of file
diff --git a/docs/index.xml b/docs/index.xml
index 36b9396..d2cf012 100644
--- a/docs/index.xml
+++ b/docs/index.xml
@@ -52,7 +52,7 @@ The relay server can be the local email server, a specific host or a third-party
       
       <guid>https://lettre.github.io/lettre/sending-messages/sendmail/</guid>
       <description>The sendmail transport sends the email using the local sendmail command.
-extern crate lettre; use lettre::sendmail::SendmailTransport; use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress}; fn main() { let email = SimpleSendableEmail::new( EmailAddress::new(&amp;#34;user@localhost&amp;#34;.to_string()), vec![EmailAddress::new(&amp;#34;root@localhost&amp;#34;.to_string())], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ); let mut sender = SendmailTransport::new(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); }</description>
+extern crate lettre; use lettre::sendmail::SendmailTransport; use lettre::{SimpleSendableEmail, EmailTransport}; fn main() { let email = SimpleSendableEmail::new( &amp;#34;user@localhost&amp;#34;.to_string(), &amp;amp;[&amp;#34;root@localhost&amp;#34;.to_string()], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ).unwrap(); let mut sender = SendmailTransport::new(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); }</description>
     </item>
     
     <item>
@@ -72,7 +72,7 @@ extern crate lettre_email; use lettre_email::EmailBuilder; fn main() { // Create
       
       <guid>https://lettre.github.io/lettre/sending-messages/file/</guid>
       <description>The file transport writes the emails to the given directory. The name of the file will be message_id.txt. It can be useful for testing purposes, or if you want to keep track of sent messages.
-extern crate lettre; use std::env::temp_dir; use lettre::file::FileEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress}; fn main() { // Write to the local temp directory  let mut sender = FileEmailTransport::new(temp_dir()); let email = SimpleSendableEmail::new( EmailAddress::new(&amp;#34;user@localhost&amp;#34;.to_string()), vec![EmailAddress::new(&amp;#34;root@localhost&amp;#34;.to_string())], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.</description>
+extern crate lettre; use std::env::temp_dir; use lettre::file::FileEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport}; fn main() { // Write to the local temp directory  let mut sender = FileEmailTransport::new(temp_dir()); let email = SimpleSendableEmail::new( &amp;#34;user@localhost&amp;#34;.to_string(), &amp;amp;[&amp;#34;root@localhost&amp;#34;.to_string()], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ).</description>
     </item>
     
     <item>
@@ -82,7 +82,7 @@ extern crate lettre; use std::env::temp_dir; use lettre::file::FileEmailTranspor
       
       <guid>https://lettre.github.io/lettre/sending-messages/stub/</guid>
       <description>The stub transport only logs message envelope and drops the content. It can be useful for testing purposes.
-extern crate lettre; use lettre::stub::StubEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress}; fn main() { let email = SimpleSendableEmail::new( EmailAddress::new(&amp;#34;user@localhost&amp;#34;.to_string()), vec![EmailAddress::new(&amp;#34;root@localhost&amp;#34;.to_string())], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ); let mut sender = StubEmailTransport::new_positive(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); } Will log (when using a logger like env_logger):
+extern crate lettre; use lettre::stub::StubEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport}; fn main() { let email = SimpleSendableEmail::new( &amp;#34;user@localhost&amp;#34;.to_string(), &amp;amp;[&amp;#34;root@localhost&amp;#34;.to_string()], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ).unwrap(); let mut sender = StubEmailTransport::new_positive(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); } Will log (when using a logger like env_logger):
 b7c211bc-9811-45ce-8cd9-68eab575d695: from=&amp;lt;user@localhost&amp;gt; to=&amp;lt;root@localhost&amp;gt;</description>
     </item>
     
diff --git a/docs/sending-messages/file/index.html b/docs/sending-messages/file/index.html
index af8d4b6..9572ddb 100644
--- a/docs/sending-messages/file/index.html
+++ b/docs/sending-messages/file/index.html
@@ -12,17 +12,17 @@
     <title>File transport :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -391,17 +391,17 @@ It can be useful for testing purposes, or if you want to keep track of sent mess
 <span style="color:#66d9ef">use</span> std::env::temp_dir;
 
 <span style="color:#66d9ef">use</span> lettre::file::FileEmailTransport;
-<span style="color:#66d9ef">use</span> lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};
+<span style="color:#66d9ef">use</span> lettre::{SimpleSendableEmail, EmailTransport};
 
 <span style="color:#66d9ef">fn</span> <span style="color:#a6e22e">main</span>() {
     <span style="color:#75715e">// Write to the local temp directory
 </span><span style="color:#75715e"></span>    <span style="color:#66d9ef">let</span> <span style="color:#66d9ef">mut</span> sender <span style="color:#f92672">=</span> FileEmailTransport::new(temp_dir());
     <span style="color:#66d9ef">let</span> email <span style="color:#f92672">=</span> SimpleSendableEmail::new(
-                    EmailAddress::new(<span style="color:#e6db74">&#34;user@localhost&#34;</span>.to_string()),
-                    vec<span style="color:#f92672">!</span>[EmailAddress::new(<span style="color:#e6db74">&#34;root@localhost&#34;</span>.to_string())],
+                    <span style="color:#e6db74">&#34;user@localhost&#34;</span>.to_string(),
+                    <span style="color:#f92672">&amp;</span>[<span style="color:#e6db74">&#34;root@localhost&#34;</span>.to_string()],
                     <span style="color:#e6db74">&#34;message_id&#34;</span>.to_string(),
                     <span style="color:#e6db74">&#34;Hello world&#34;</span>.to_string(),
-                );
+                ).unwrap();
     
     <span style="color:#66d9ef">let</span> result <span style="color:#f92672">=</span> sender.send(<span style="color:#f92672">&amp;</span>email);
     assert<span style="color:#f92672">!</span>(result.is_ok());
@@ -635,20 +635,20 @@ Hello World!</code></pre></div>
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/sending-messages/index.html b/docs/sending-messages/index.html
index 953e466..3c2dd03 100644
--- a/docs/sending-messages/index.html
+++ b/docs/sending-messages/index.html
@@ -12,17 +12,17 @@
     <title>Sending messages :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -608,20 +608,20 @@
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/sending-messages/index.xml b/docs/sending-messages/index.xml
index 481d829..3f6e045 100644
--- a/docs/sending-messages/index.xml
+++ b/docs/sending-messages/index.xml
@@ -41,7 +41,7 @@ The relay server can be the local email server, a specific host or a third-party
       
       <guid>https://lettre.github.io/lettre/sending-messages/sendmail/</guid>
       <description>The sendmail transport sends the email using the local sendmail command.
-extern crate lettre; use lettre::sendmail::SendmailTransport; use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress}; fn main() { let email = SimpleSendableEmail::new( EmailAddress::new(&amp;#34;user@localhost&amp;#34;.to_string()), vec![EmailAddress::new(&amp;#34;root@localhost&amp;#34;.to_string())], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ); let mut sender = SendmailTransport::new(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); }</description>
+extern crate lettre; use lettre::sendmail::SendmailTransport; use lettre::{SimpleSendableEmail, EmailTransport}; fn main() { let email = SimpleSendableEmail::new( &amp;#34;user@localhost&amp;#34;.to_string(), &amp;amp;[&amp;#34;root@localhost&amp;#34;.to_string()], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ).unwrap(); let mut sender = SendmailTransport::new(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); }</description>
     </item>
     
     <item>
@@ -51,7 +51,7 @@ extern crate lettre; use lettre::sendmail::SendmailTransport; use lettre::{Simpl
       
       <guid>https://lettre.github.io/lettre/sending-messages/file/</guid>
       <description>The file transport writes the emails to the given directory. The name of the file will be message_id.txt. It can be useful for testing purposes, or if you want to keep track of sent messages.
-extern crate lettre; use std::env::temp_dir; use lettre::file::FileEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress}; fn main() { // Write to the local temp directory  let mut sender = FileEmailTransport::new(temp_dir()); let email = SimpleSendableEmail::new( EmailAddress::new(&amp;#34;user@localhost&amp;#34;.to_string()), vec![EmailAddress::new(&amp;#34;root@localhost&amp;#34;.to_string())], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.</description>
+extern crate lettre; use std::env::temp_dir; use lettre::file::FileEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport}; fn main() { // Write to the local temp directory  let mut sender = FileEmailTransport::new(temp_dir()); let email = SimpleSendableEmail::new( &amp;#34;user@localhost&amp;#34;.to_string(), &amp;amp;[&amp;#34;root@localhost&amp;#34;.to_string()], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ).</description>
     </item>
     
     <item>
@@ -61,7 +61,7 @@ extern crate lettre; use std::env::temp_dir; use lettre::file::FileEmailTranspor
       
       <guid>https://lettre.github.io/lettre/sending-messages/stub/</guid>
       <description>The stub transport only logs message envelope and drops the content. It can be useful for testing purposes.
-extern crate lettre; use lettre::stub::StubEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress}; fn main() { let email = SimpleSendableEmail::new( EmailAddress::new(&amp;#34;user@localhost&amp;#34;.to_string()), vec![EmailAddress::new(&amp;#34;root@localhost&amp;#34;.to_string())], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ); let mut sender = StubEmailTransport::new_positive(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); } Will log (when using a logger like env_logger):
+extern crate lettre; use lettre::stub::StubEmailTransport; use lettre::{SimpleSendableEmail, EmailTransport}; fn main() { let email = SimpleSendableEmail::new( &amp;#34;user@localhost&amp;#34;.to_string(), &amp;amp;[&amp;#34;root@localhost&amp;#34;.to_string()], &amp;#34;message_id&amp;#34;.to_string(), &amp;#34;Hello world&amp;#34;.to_string(), ).unwrap(); let mut sender = StubEmailTransport::new_positive(); let result = sender.send(&amp;amp;email); assert!(result.is_ok()); } Will log (when using a logger like env_logger):
 b7c211bc-9811-45ce-8cd9-68eab575d695: from=&amp;lt;user@localhost&amp;gt; to=&amp;lt;root@localhost&amp;gt;</description>
     </item>
     
diff --git a/docs/sending-messages/intro/index.html b/docs/sending-messages/intro/index.html
index 27028bb..b2294bd 100644
--- a/docs/sending-messages/intro/index.html
+++ b/docs/sending-messages/intro/index.html
@@ -12,17 +12,17 @@
     <title>Introduction :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -616,20 +616,20 @@ logs.</li>
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/sending-messages/sendmail/index.html b/docs/sending-messages/sendmail/index.html
index 1143fa1..93eb310 100644
--- a/docs/sending-messages/sendmail/index.html
+++ b/docs/sending-messages/sendmail/index.html
@@ -12,17 +12,17 @@
     <title>Sendmail transport :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -387,15 +387,15 @@
 <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-rust,no_run" data-lang="rust,no_run">extern crate lettre;
 
 use lettre::sendmail::SendmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};
+use lettre::{SimpleSendableEmail, EmailTransport};
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new(&#34;user@localhost&#34;.to_string()),
-                    vec![EmailAddress::new(&#34;root@localhost&#34;.to_string())],
+                    &#34;user@localhost&#34;.to_string(),
+                    &amp;[&#34;root@localhost&#34;.to_string()],
                     &#34;message_id&#34;.to_string(),
                     &#34;Hello world&#34;.to_string(),
-                );
+                ).unwrap();
     
     let mut sender = SendmailTransport::new();
     let result = sender.send(&amp;email);
@@ -621,20 +621,20 @@ fn main() {
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/sending-messages/smtp/index.html b/docs/sending-messages/smtp/index.html
index c472ac3..3ebeeef 100644
--- a/docs/sending-messages/smtp/index.html
+++ b/docs/sending-messages/smtp/index.html
@@ -12,17 +12,17 @@
     <title>SMTP transport :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -420,15 +420,15 @@ emails directly to the destination.</p>
 <p>This is the most basic example of usage:</p>
 <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-rust,no_run" data-lang="rust,no_run">extern crate lettre;
 
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress, SmtpTransport};
+use lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new(&#34;user@localhost&#34;.to_string()),
-                    vec![EmailAddress::new(&#34;root@localhost&#34;.to_string())],
+                    &#34;user@localhost&#34;.to_string(),
+                    &amp;[&#34;root@localhost&#34;.to_string()],
                     &#34;message_id&#34;.to_string(),
                     &#34;Hello world&#34;.to_string(),
-                );
+                ).unwrap();
     
     // Open a local connection on port 25
     let mut mailer =
@@ -442,17 +442,17 @@ fn main() {
 <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-rust,no_run" data-lang="rust,no_run">extern crate lettre;
 
 use lettre::smtp::authentication::{Credentials, Mechanism};
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress, SmtpTransport};
+use lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};
 use lettre::smtp::extension::ClientId;
 use lettre::smtp::ConnectionReuseParameters;
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new(&#34;user@localhost&#34;.to_string()),
-                    vec![EmailAddress::new(&#34;root@localhost&#34;.to_string())],
+                    &#34;user@localhost&#34;.to_string(),
+                    &amp;[&#34;root@localhost&#34;.to_string()],
                     &#34;message_id&#34;.to_string(),
                     &#34;Hello world&#34;.to_string(),
-                );
+                ).unwrap();
     
     // Connect to a remote server on a custom port
     let mut mailer = SmtpTransport::simple_builder(&#34;server.tld&#34;).unwrap()
@@ -495,10 +495,10 @@ fn main() {
     let _ = email_client.connect(&amp;(&#34;localhost&#34;, SMTP_PORT), None);
     let _ = email_client.command(EhloCommand::new(ClientId::new(&#34;my_hostname&#34;.to_string())));
     let _ = email_client.command(
-                MailCommand::new(Some(EmailAddress::new(&#34;user@example.com&#34;.to_string())), vec![])
+                MailCommand::new(Some(EmailAddress::new(&#34;user@example.com&#34;.to_string()).unwrap()), vec![])
             );
     let _ = email_client.command(
-                RcptCommand::new(EmailAddress::new(&#34;user@example.org&#34;.to_string()), vec![])
+                RcptCommand::new(EmailAddress::new(&#34;user@example.org&#34;.to_string()).unwrap(), vec![])
             );
     let _ = email_client.command(DataCommand);
     let _ = email_client.message(Box::new(&#34;Test email&#34;.as_bytes()));
@@ -724,20 +724,20 @@ fn main() {
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/docs/sending-messages/stub/index.html b/docs/sending-messages/stub/index.html
index 9e707d2..c04819a 100644
--- a/docs/sending-messages/stub/index.html
+++ b/docs/sending-messages/stub/index.html
@@ -12,17 +12,17 @@
     <title>Stub transport :: Lettre site</title>
     
     
-    <link href="/lettre/css/nucleus.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/font-awesome.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hybrid.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/featherlight.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/perfect-scrollbar.min.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/auto-complete.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/theme.css?1517057321" rel="stylesheet">
-    <link href="/lettre/css/hugo-theme.css?1517057321" rel="stylesheet">
+    <link href="/lettre/css/nucleus.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/font-awesome.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hybrid.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/featherlight.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/perfect-scrollbar.min.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/auto-complete.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/theme.css?1522506318" rel="stylesheet">
+    <link href="/lettre/css/hugo-theme.css?1522506318" rel="stylesheet">
     
 
-    <script src="/lettre/js/jquery-2.x.min.js?1517057321"></script>
+    <script src="/lettre/js/jquery-2.x.min.js?1522506318"></script>
     
     <style type="text/css">
       :root #header + #content > #left > #rlblock_left{ 
@@ -49,14 +49,14 @@
     <span data-search-clear=""><i class="fa fa-close"></i></span>
 </div>
 
-<script type="text/javascript" src="/lettre/js/lunr.min.js?1517057321"></script>
-<script type="text/javascript" src="/lettre/js/auto-complete.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/lunr.min.js?1522506318"></script>
+<script type="text/javascript" src="/lettre/js/auto-complete.js?1522506318"></script>
 <script type="text/javascript">
     
         var baseurl = "https:\/\/lettre.github.io\/lettre";
     
 </script>
-<script type="text/javascript" src="/lettre/js/search.js?1517057321"></script>
+<script type="text/javascript" src="/lettre/js/search.js?1522506318"></script>
 
     
   </div>
@@ -388,15 +388,15 @@ testing purposes.</p>
 <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-rust" data-lang="rust"><span style="color:#66d9ef">extern</span> <span style="color:#66d9ef">crate</span> lettre;
 
 <span style="color:#66d9ef">use</span> lettre::stub::StubEmailTransport;
-<span style="color:#66d9ef">use</span> lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};
+<span style="color:#66d9ef">use</span> lettre::{SimpleSendableEmail, EmailTransport};
 
 <span style="color:#66d9ef">fn</span> <span style="color:#a6e22e">main</span>() {
     <span style="color:#66d9ef">let</span> email <span style="color:#f92672">=</span> SimpleSendableEmail::new(
-                    EmailAddress::new(<span style="color:#e6db74">&#34;user@localhost&#34;</span>.to_string()),
-                    vec<span style="color:#f92672">!</span>[EmailAddress::new(<span style="color:#e6db74">&#34;root@localhost&#34;</span>.to_string())],
+                    <span style="color:#e6db74">&#34;user@localhost&#34;</span>.to_string(),
+                    <span style="color:#f92672">&amp;</span>[<span style="color:#e6db74">&#34;root@localhost&#34;</span>.to_string()],
                     <span style="color:#e6db74">&#34;message_id&#34;</span>.to_string(),
                     <span style="color:#e6db74">&#34;Hello world&#34;</span>.to_string(),
-                );
+                ).unwrap();
     
     <span style="color:#66d9ef">let</span> <span style="color:#66d9ef">mut</span> sender <span style="color:#f92672">=</span> StubEmailTransport::new_positive();
     <span style="color:#66d9ef">let</span> result <span style="color:#f92672">=</span> sender.send(<span style="color:#f92672">&amp;</span>email);
@@ -621,20 +621,20 @@ testing purposes.</p>
     <div style="left: -1000px; overflow: scroll; position: absolute; top: -1000px; border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;">
       <div style="border: none; box-sizing: content-box; height: 200px; margin: 0px; padding: 0px; width: 200px;"></div>
     </div>
-    <script src="/lettre/js/clipboard.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.min.js?1517057321"></script>
-    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1517057321"></script>
-    <script src="/lettre/js/jquery.sticky-kit.min.js?1517057321"></script>
-    <script src="/lettre/js/featherlight.min.js?1517057321"></script>
-    <script src="/lettre/js/html5shiv-printshiv.min.js?1517057321"></script>
-    <script src="/lettre/js/highlight.pack.js?1517057321"></script>
+    <script src="/lettre/js/clipboard.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.min.js?1522506318"></script>
+    <script src="/lettre/js/perfect-scrollbar.jquery.min.js?1522506318"></script>
+    <script src="/lettre/js/jquery.sticky-kit.min.js?1522506318"></script>
+    <script src="/lettre/js/featherlight.min.js?1522506318"></script>
+    <script src="/lettre/js/html5shiv-printshiv.min.js?1522506318"></script>
+    <script src="/lettre/js/highlight.pack.js?1522506318"></script>
     <script>hljs.initHighlightingOnLoad();</script>
-    <script src="/lettre/js/modernizr.custom.71422.js?1517057321"></script>
-    <script src="/lettre/js/learn.js?1517057321"></script>
-    <script src="/lettre/js/hugo-learn.js?1517057321"></script>
+    <script src="/lettre/js/modernizr.custom.71422.js?1522506318"></script>
+    <script src="/lettre/js/learn.js?1522506318"></script>
+    <script src="/lettre/js/hugo-learn.js?1522506318"></script>
 
-    <link href="/lettre/mermaid/mermaid.css?1517057321" type="text/css" rel="stylesheet" />
-    <script src="/lettre/mermaid/mermaid.js?1517057321"></script>
+    <link href="/lettre/mermaid/mermaid.css?1522506318" type="text/css" rel="stylesheet" />
+    <script src="/lettre/mermaid/mermaid.js?1522506318"></script>
     <script>
         mermaid.initialize({ startOnLoad: true });
     </script>
diff --git a/lettre/CHANGELOG.md b/lettre/CHANGELOG.md
index 0a8b287..43df181 100644
--- a/lettre/CHANGELOG.md
+++ b/lettre/CHANGELOG.md
@@ -11,6 +11,10 @@
 
 * Detail in SMTP Response is now an enum
 * Use nom for parsing smtp responses
+* `Envelope` was moved from `lettre_email` to `lettre`
+* `EmailAddress::new()` now returns a `Result`
+* `SendableEmail` replaces `from` and `to` by `envelope` that returns an `Envelope`
+* `File` transport storage format has changed
 
 #### Removed
 
diff --git a/lettre/examples/smtp.rs b/lettre/examples/smtp.rs
index 2d585a2..51eff1b 100644
--- a/lettre/examples/smtp.rs
+++ b/lettre/examples/smtp.rs
@@ -1,17 +1,17 @@
 extern crate env_logger;
 extern crate lettre;
 
-use lettre::{EmailAddress, EmailTransport, SimpleSendableEmail, SmtpTransport};
+use lettre::{EmailTransport, SimpleSendableEmail, SmtpTransport};
 
 fn main() {
     env_logger::init();
 
     let email = SimpleSendableEmail::new(
-        EmailAddress::new("user@localhost".to_string()),
-        vec![EmailAddress::new("root@localhost".to_string())],
-        "file_id".to_string(),
+        "user@localhost".to_string(),
+        &["root@localhost".to_string()],
+        "my-message-id".to_string(),
         "Hello ß☺ example".to_string(),
-    );
+    ).unwrap();
 
     // Open a local connection on port 25
     let mut mailer = SmtpTransport::builder_unencrypted_localhost()
diff --git a/lettre/src/file/mod.rs b/lettre/src/file/mod.rs
index 0d3fcbb..34596db 100644
--- a/lettre/src/file/mod.rs
+++ b/lettre/src/file/mod.rs
@@ -40,10 +40,9 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, FileResult> for FileEmailTransport
         let mut message_content = String::new();
         let _ = email.message().read_to_string(&mut message_content);
 
-        let simple_email = SimpleSendableEmail::new(
-            email.from().clone(),
-            email.to().clone(),
-            email.message_id().clone(),
+        let simple_email = SimpleSendableEmail::new_with_envelope(
+            email.envelope().clone(),
+            email.message_id().to_string(),
             message_content,
         );
 
diff --git a/lettre/src/lib.rs b/lettre/src/lib.rs
index 0f609b0..62aa6a6 100644
--- a/lettre/src/lib.rs
+++ b/lettre/src/lib.rs
@@ -48,11 +48,63 @@ pub use smtp::{ClientSecurity, SmtpTransport};
 pub use smtp::client::net::ClientTlsParameters;
 use std::fmt::{self, Display, Formatter};
 use std::io::Read;
+use std::error::Error as StdError;
+use std::str::FromStr;
+
+/// Error type for email content
+#[derive(Debug)]
+pub enum Error {
+    /// Missing from in envelope
+    MissingFrom,
+    /// Missing to in envelope
+    MissingTo,
+    /// Invalid email
+    InvalidEmailAddress,
+}
+
+impl StdError for Error {
+    fn description(&self) -> &str {
+        match *self {
+            Error::MissingFrom => "missing source address, invalid envelope",
+            Error::MissingTo => "missing destination address, invalid envelope",
+            Error::InvalidEmailAddress => "invalid email address",
+        }
+    }
+
+    fn cause(&self) -> Option<&StdError> {
+        None
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), fmt::Error> {
+        fmt.write_str(self.description())
+    }
+}
+
+/// Email result type
+pub type EmailResult<T> = Result<T, Error>;
 
 /// Email address
 #[derive(PartialEq, Eq, Clone, Debug)]
 #[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
-pub struct EmailAddress(pub String);
+pub struct EmailAddress(String);
+
+impl EmailAddress {
+    /// Creates a new `EmailAddress`. For now it makes no validation.
+    pub fn new(address: String) -> EmailResult<EmailAddress> {
+        // TODO make some basic sanity checks
+        Ok(EmailAddress(address))
+    }
+}
+
+impl FromStr for EmailAddress {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        EmailAddress::new(s.to_string())
+    }
+}
 
 impl Display for EmailAddress {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
@@ -60,19 +112,98 @@ impl Display for EmailAddress {
     }
 }
 
-impl EmailAddress {
-    /// Creates a new email address
-    pub fn new(address: String) -> EmailAddress {
-        EmailAddress(address)
+/// Simple email envelope representation
+///
+/// We only accept mailboxes, and do not support source routes (as per RFC).
+#[derive(PartialEq, Eq, Clone, Debug)]
+#[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
+pub struct Envelope {
+    /// The envelope recipients' addresses
+    ///
+    /// This can not be empty.
+    forward_path: Vec<EmailAddress>,
+    /// The envelope sender address
+    reverse_path: Option<EmailAddress>,
+}
+
+impl Envelope {
+    /// Creates a new envelope, which may fail if `to` is empty.
+    pub fn new(from: Option<EmailAddress>, to: Vec<EmailAddress>) -> EmailResult<Envelope> {
+        if to.is_empty() {
+            return Err(Error::MissingTo);
+        }
+        Ok(Envelope {
+            forward_path: to,
+            reverse_path: from,
+        })
+    }
+
+    /// Destination addresses of the envelope
+    pub fn to(&self) -> &[EmailAddress] {
+        self.forward_path.as_slice()
+    }
+
+    /// Source address of the envelope
+    pub fn from(&self) -> Option<&EmailAddress> {
+        self.reverse_path.as_ref()
+    }
+
+    /// Creates a new builder
+    pub fn builder() -> EnvelopeBuilder {
+        EnvelopeBuilder::new()
+    }
+}
+
+/// Simple email envelope representation
+#[derive(PartialEq, Eq, Clone, Debug, Default)]
+pub struct EnvelopeBuilder {
+    /// The envelope recipients' addresses
+    to: Vec<EmailAddress>,
+    /// The envelope sender address
+    from: Option<EmailAddress>,
+}
+
+impl EnvelopeBuilder {
+    /// Constructs an envelope with no recipients and an empty sender
+    pub fn new() -> Self {
+        EnvelopeBuilder {
+            to: vec![],
+            from: None,
+        }
+    }
+
+    /// Adds a recipient
+    pub fn to<S: Into<EmailAddress>>(mut self, address: S) -> Self {
+        self.add_to(address);
+        self
+    }
+
+    /// Adds a recipient
+    pub fn add_to<S: Into<EmailAddress>>(&mut self, address: S) {
+        self.to.push(address.into());
+    }
+
+    /// Sets the sender
+    pub fn from<S: Into<EmailAddress>>(mut self, address: S) -> Self {
+        self.set_from(address);
+        self
+    }
+
+    /// Sets the sender
+    pub fn set_from<S: Into<EmailAddress>>(&mut self, address: S) {
+        self.from = Some(address.into());
+    }
+
+    /// Build the envelope
+    pub fn build(self) -> EmailResult<Envelope> {
+        Envelope::new(self.from, self.to)
     }
 }
 
 /// Email sendable by an SMTP client
 pub trait SendableEmail<'a, T: Read + 'a> {
-    /// To
-    fn to(&self) -> Vec<EmailAddress>;
-    /// From
-    fn from(&self) -> EmailAddress;
+    /// Envelope
+    fn envelope(&self) -> Envelope;
     /// Message ID, used for logging
     fn message_id(&self) -> String;
     /// Message content
@@ -89,10 +220,8 @@ pub trait EmailTransport<'a, U: Read + 'a, V> {
 #[derive(Debug, Clone)]
 #[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
 pub struct SimpleSendableEmail {
-    /// To
-    to: Vec<EmailAddress>,
-    /// From
-    from: EmailAddress,
+    /// Envelope
+    envelope: Envelope,
     /// Message ID
     message_id: String,
     /// Message content
@@ -102,14 +231,30 @@ pub struct SimpleSendableEmail {
 impl SimpleSendableEmail {
     /// Returns a new email
     pub fn new(
-        from_address: EmailAddress,
-        to_addresses: Vec<EmailAddress>,
+        from_address: String,
+        to_addresses: &[String],
+        message_id: String,
+        message: String,
+    ) -> EmailResult<SimpleSendableEmail> {
+        let to: Result<Vec<EmailAddress>, Error> = to_addresses
+            .iter()
+            .map(|x| EmailAddress::new(x.clone()))
+            .collect();
+        Ok(SimpleSendableEmail::new_with_envelope(
+            Envelope::new(Some(EmailAddress::new(from_address)?), to?)?,
+            message_id,
+            message,
+        ))
+    }
+
+    /// Returns a new email from a valid envelope
+    pub fn new_with_envelope(
+        envelope: Envelope,
         message_id: String,
         message: String,
     ) -> SimpleSendableEmail {
         SimpleSendableEmail {
-            from: from_address,
-            to: to_addresses,
+            envelope,
             message_id,
             message: message.into_bytes(),
         }
@@ -117,12 +262,8 @@ impl SimpleSendableEmail {
 }
 
 impl<'a> SendableEmail<'a, &'a [u8]> for SimpleSendableEmail {
-    fn to(&self) -> Vec<EmailAddress> {
-        self.to.clone()
-    }
-
-    fn from(&self) -> EmailAddress {
-        self.from.clone()
+    fn envelope(&self) -> Envelope {
+        self.envelope.clone()
     }
 
     fn message_id(&self) -> String {
diff --git a/lettre/src/sendmail/mod.rs b/lettre/src/sendmail/mod.rs
index 03dcb26..e9986c0 100644
--- a/lettre/src/sendmail/mod.rs
+++ b/lettre/src/sendmail/mod.rs
@@ -33,13 +33,18 @@ impl SendmailTransport {
 
 impl<'a, T: Read + 'a> EmailTransport<'a, T, SendmailResult> for SendmailTransport {
     fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> SendmailResult {
+        let envelope = email.envelope();
+
         // Spawn the sendmail command
-        let to_addresses: Vec<String> = email.to().iter().map(|x| x.to_string()).collect();
+        let to_addresses: Vec<String> = envelope.to().iter().map(|x| x.to_string()).collect();
         let mut process = Command::new(&self.command)
             .args(&[
                 "-i",
                 "-f",
-                &email.from().to_string(),
+                &match envelope.from() {
+                    Some(address) => address.to_string(),
+                    None => "\"\"".to_string(),
+                },
                 &to_addresses.join(" "),
             ])
             .stdin(Stdio::piped())
diff --git a/lettre/src/smtp/commands.rs b/lettre/src/smtp/commands.rs
index 357133f..e8ea924 100644
--- a/lettre/src/smtp/commands.rs
+++ b/lettre/src/smtp/commands.rs
@@ -307,7 +307,7 @@ mod test {
     #[test]
     fn test_display() {
         let id = ClientId::Domain("localhost".to_string());
-        let email = EmailAddress::new("test@example.com".to_string());
+        let email = EmailAddress::new("test@example.com".to_string()).unwrap();
         let mail_parameter = MailParameter::Other {
             keyword: "TEST".to_string(),
             value: Some("value".to_string()),
diff --git a/lettre/src/smtp/mod.rs b/lettre/src/smtp/mod.rs
index 2eded34..8f8856f 100644
--- a/lettre/src/smtp/mod.rs
+++ b/lettre/src/smtp/mod.rs
@@ -308,6 +308,7 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
     fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> SmtpResult {
         // Extract email information
         let message_id = email.message_id();
+        let envelope = email.envelope();
 
         // Check if the connection is still available
         if (self.state.connection_reuse_count > 0) && (!self.client.is_connected()) {
@@ -413,15 +414,22 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
 
         try_smtp!(
             self.client
-                .command(MailCommand::new(Some(email.from().clone()), mail_options,)),
+                .command(MailCommand::new(envelope.from().cloned(), mail_options,)),
             self
         );
 
         // Log the mail command
-        info!("{}: from=<{}>", message_id, email.from());
+        info!(
+            "{}: from=<{}>",
+            message_id,
+            match envelope.from() {
+                Some(address) => address.to_string(),
+                None => "".to_string(),
+            }
+        );
 
         // Recipient
-        for to_address in &email.to() {
+        for to_address in envelope.to() {
             try_smtp!(
                 self.client
                     .command(RcptCommand::new(to_address.clone(), vec![]),),
diff --git a/lettre/src/smtp/response.rs b/lettre/src/smtp/response.rs
index d632a70..3bd2611 100644
--- a/lettre/src/smtp/response.rs
+++ b/lettre/src/smtp/response.rs
@@ -53,16 +53,26 @@ impl Display for Category {
 /// The detail digit of a response code (third digit)
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
 pub enum Detail {
-    #[allow(missing_docs)] Zero = 0,
-    #[allow(missing_docs)] One = 1,
-    #[allow(missing_docs)] Two = 2,
-    #[allow(missing_docs)] Three = 3,
-    #[allow(missing_docs)] Four = 4,
-    #[allow(missing_docs)] Five = 5,
-    #[allow(missing_docs)] Six = 6,
-    #[allow(missing_docs)] Seven = 7,
-    #[allow(missing_docs)] Eight = 8,
-    #[allow(missing_docs)] Nine = 9,
+    #[allow(missing_docs)]
+    Zero = 0,
+    #[allow(missing_docs)]
+    One = 1,
+    #[allow(missing_docs)]
+    Two = 2,
+    #[allow(missing_docs)]
+    Three = 3,
+    #[allow(missing_docs)]
+    Four = 4,
+    #[allow(missing_docs)]
+    Five = 5,
+    #[allow(missing_docs)]
+    Six = 6,
+    #[allow(missing_docs)]
+    Seven = 7,
+    #[allow(missing_docs)]
+    Eight = 8,
+    #[allow(missing_docs)]
+    Nine = 9,
 }
 
 impl Display for Detail {
diff --git a/lettre/src/stub/mod.rs b/lettre/src/stub/mod.rs
index 3bf5b9b..ae5595b 100644
--- a/lettre/src/stub/mod.rs
+++ b/lettre/src/stub/mod.rs
@@ -29,11 +29,15 @@ pub type StubResult = Result<(), ()>;
 
 impl<'a, T: Read + 'a> EmailTransport<'a, T, StubResult> for StubEmailTransport {
     fn send<U: SendableEmail<'a, T>>(&mut self, email: &'a U) -> StubResult {
+        let envelope = email.envelope();
         info!(
             "{}: from=<{}> to=<{:?}>",
             email.message_id(),
-            email.from(),
-            email.to()
+            match envelope.from() {
+                Some(address) => address.to_string(),
+                None => "".to_string(),
+            },
+            envelope.to()
         );
         self.response
     }
diff --git a/lettre/tests/transport_file.rs b/lettre/tests/transport_file.rs
index f8bb3a3..9dc1a82 100644
--- a/lettre/tests/transport_file.rs
+++ b/lettre/tests/transport_file.rs
@@ -4,7 +4,7 @@ extern crate lettre;
 #[cfg(feature = "file-transport")]
 mod test {
 
-    use lettre::{EmailAddress, EmailTransport, SendableEmail, SimpleSendableEmail};
+    use lettre::{EmailTransport, SendableEmail, SimpleSendableEmail};
     use lettre::file::FileEmailTransport;
     use std::env::temp_dir;
     use std::fs::File;
@@ -15,11 +15,11 @@ mod test {
     fn file_transport() {
         let mut sender = FileEmailTransport::new(temp_dir());
         let email = SimpleSendableEmail::new(
-            EmailAddress::new("user@localhost".to_string()),
-            vec![EmailAddress::new("root@localhost".to_string())],
+            "user@localhost".to_string(),
+            &["root@localhost".to_string()],
             "file_id".to_string(),
             "Hello file".to_string(),
-        );
+        ).unwrap();
         let result = sender.send(&email);
         assert!(result.is_ok());
 
@@ -31,8 +31,7 @@ mod test {
 
         assert_eq!(
             buffer,
-            "{\"to\":[\"root@localhost\"],\"from\":\"user@localhost\",\"message_id\":\
-             \"file_id\",\"message\":[72,101,108,108,111,32,102,105,108,101]}"
+            "{\"envelope\":{\"forward_path\":[\"root@localhost\"],\"reverse_path\":\"user@localhost\"},\"message_id\":\"file_id\",\"message\":[72,101,108,108,111,32,102,105,108,101]}"
         );
 
         remove_file(file).unwrap();
diff --git a/lettre/tests/transport_sendmail.rs b/lettre/tests/transport_sendmail.rs
index 8c7cc80..0d8109b 100644
--- a/lettre/tests/transport_sendmail.rs
+++ b/lettre/tests/transport_sendmail.rs
@@ -4,18 +4,18 @@ extern crate lettre;
 #[cfg(feature = "sendmail-transport")]
 mod test {
 
-    use lettre::{EmailAddress, EmailTransport, SimpleSendableEmail};
+    use lettre::{EmailTransport, SimpleSendableEmail};
     use lettre::sendmail::SendmailTransport;
 
     #[test]
     fn sendmail_transport_simple() {
         let mut sender = SendmailTransport::new();
         let email = SimpleSendableEmail::new(
-            EmailAddress::new("user@localhost".to_string()),
-            vec![EmailAddress::new("root@localhost".to_string())],
+            "user@localhost".to_string(),
+            &["root@localhost".to_string()],
             "sendmail_id".to_string(),
             "Hello sendmail".to_string(),
-        );
+        ).unwrap();
 
         let result = sender.send(&email);
         println!("{:?}", result);
diff --git a/lettre/tests/transport_smtp.rs b/lettre/tests/transport_smtp.rs
index 236b382..25fdc14 100644
--- a/lettre/tests/transport_smtp.rs
+++ b/lettre/tests/transport_smtp.rs
@@ -4,7 +4,7 @@ extern crate lettre;
 #[cfg(feature = "smtp-transport")]
 mod test {
 
-    use lettre::{ClientSecurity, EmailAddress, EmailTransport, SimpleSendableEmail, SmtpTransport};
+    use lettre::{ClientSecurity, EmailTransport, SimpleSendableEmail, SmtpTransport};
 
     #[test]
     fn smtp_transport_simple() {
@@ -12,11 +12,11 @@ mod test {
             .unwrap()
             .build();
         let email = SimpleSendableEmail::new(
-            EmailAddress::new("user@localhost".to_string()),
-            vec![EmailAddress::new("root@localhost".to_string())],
+            "user@localhost".to_string(),
+            &["root@localhost".to_string()],
             "smtp_id".to_string(),
             "Hello smtp".to_string(),
-        );
+        ).unwrap();
 
         sender.send(&email).unwrap();
     }
diff --git a/lettre/tests/transport_stub.rs b/lettre/tests/transport_stub.rs
index 23976cf..b9a38cd 100644
--- a/lettre/tests/transport_stub.rs
+++ b/lettre/tests/transport_stub.rs
@@ -1,19 +1,18 @@
 extern crate lettre;
 
-use lettre::{EmailAddress, EmailTransport, SimpleSendableEmail};
+use lettre::{EmailTransport, SimpleSendableEmail};
 use lettre::stub::StubEmailTransport;
 
 #[test]
 fn stub_transport() {
     let mut sender_ok = StubEmailTransport::new_positive();
     let mut sender_ko = StubEmailTransport::new(Err(()));
-
     let email = SimpleSendableEmail::new(
-        EmailAddress::new("user@localhost".to_string()),
-        vec![EmailAddress::new("root@localhost".to_string())],
+        "user@localhost".to_string(),
+        &["root@localhost".to_string()],
         "stub_id".to_string(),
         "Hello stub".to_string(),
-    );
+    ).unwrap();
 
     sender_ok.send(&email).unwrap();
     sender_ko.send(&email).unwrap_err();
diff --git a/lettre_email/CHANGELOG.md b/lettre_email/CHANGELOG.md
index 14e20c6..3ea5af0 100644
--- a/lettre_email/CHANGELOG.md
+++ b/lettre_email/CHANGELOG.md
@@ -7,6 +7,10 @@
 * Add tests for the doc using skeptic
 * Added a code of conduct
 
+#### Changed
+
+* `Envelope` was moved from `lettre_email` to `lettre`
+
 #### Fixed
 
 * Add missing "Bcc" headers when building the email
diff --git a/lettre_email/src/error.rs b/lettre_email/src/error.rs
index 1323c65..3b3c6d9 100644
--- a/lettre_email/src/error.rs
+++ b/lettre_email/src/error.rs
@@ -5,13 +5,13 @@ use std::error::Error as StdError;
 use std::fmt::{self, Display, Formatter};
 use std::io;
 
+use lettre;
+
 /// An enum of all error kinds.
 #[derive(Debug)]
 pub enum Error {
-    /// Missing sender
-    MissingFrom,
-    /// Missing recipient
-    MissingTo,
+    /// Envelope error
+    Email(lettre::Error),
     /// Unparseable filename for attachment
     CannotParseFilename,
     /// IO error
@@ -27,8 +27,7 @@ impl Display for Error {
 impl StdError for Error {
     fn description(&self) -> &str {
         match *self {
-            MissingFrom => "the sender is missing",
-            MissingTo => "the recipient is missing",
+            Email(ref err) => err.description(),
             CannotParseFilename => "the attachment filename could not be parsed",
             Io(ref err) => err.description(),
         }
@@ -40,3 +39,9 @@ impl From<io::Error> for Error {
         Io(err)
     }
 }
+
+impl From<lettre::Error> for Error {
+    fn from(err: lettre::Error) -> Error {
+        Email(err)
+    }
+}
diff --git a/lettre_email/src/lib.rs b/lettre_email/src/lib.rs
index 4d057b2..11cb5fc 100644
--- a/lettre_email/src/lib.rs
+++ b/lettre_email/src/lib.rs
@@ -15,13 +15,14 @@ pub mod error;
 
 pub use email_format::{Address, Header, Mailbox, MimeMessage, MimeMultipartType};
 use error::Error;
-use lettre::{EmailAddress, SendableEmail};
+use lettre::{EmailAddress, Envelope, Error as EmailError, SendableEmail};
 use mime::Mime;
 use std::fs::File;
 use std::io::Read;
 use std::path::Path;
 use time::{now, Tm};
 use uuid::Uuid;
+use std::str::FromStr;
 
 /// Converts an address or an address with an alias to a `Header`
 pub trait IntoHeader {
@@ -295,43 +296,6 @@ pub struct EmailBuilder {
     date_issued: bool,
 }
 
-/// Simple email enveloppe representation
-#[derive(PartialEq, Eq, Clone, Debug, Default)]
-pub struct Envelope {
-    /// The envelope recipients' addresses
-    pub to: Vec<String>,
-    /// The envelope sender address
-    pub from: String,
-}
-
-impl Envelope {
-    /// Constructs an envelope with no receivers and an empty sender
-    pub fn new() -> Self {
-        Envelope {
-            to: vec![],
-            from: String::new(),
-        }
-    }
-    /// Adds a receiver
-    pub fn to<S: Into<String>>(mut self, address: S) -> Self {
-        self.add_to(address);
-        self
-    }
-    /// Adds a receiver
-    pub fn add_to<S: Into<String>>(&mut self, address: S) {
-        self.to.push(address.into());
-    }
-    /// Sets the sender
-    pub fn from<S: Into<String>>(mut self, address: S) -> Self {
-        self.set_from(address);
-        self
-    }
-    /// Sets the sender
-    pub fn set_from<S: Into<String>>(&mut self, address: S) {
-        self.from = address.into();
-    }
-}
-
 /// Simple email representation
 #[derive(PartialEq, Eq, Clone, Debug)]
 pub struct Email {
@@ -753,7 +717,7 @@ impl EmailBuilder {
             Some(e) => e,
             None => {
                 // we need to generate the envelope
-                let mut e = Envelope::new();
+                let mut e = Envelope::builder();
                 // add all receivers in to_header and cc_header
                 for receiver in self.to_header
                     .iter()
@@ -761,16 +725,13 @@ impl EmailBuilder {
                     .chain(self.bcc_header.iter())
                 {
                     match *receiver {
-                        Address::Mailbox(ref m) => e.add_to(m.address.clone()),
+                        Address::Mailbox(ref m) => e.add_to(EmailAddress::from_str(&m.address)?),
                         Address::Group(_, ref ms) => for m in ms.iter() {
-                            e.add_to(m.address.clone());
+                            e.add_to(EmailAddress::from_str(&m.address.clone())?);
                         },
                     }
                 }
-                if e.to.is_empty() {
-                    return Err(Error::MissingTo);
-                }
-                e.set_from(match self.sender_header {
+                e.set_from(EmailAddress::from_str(&match self.sender_header {
                     Some(x) => x.address.clone(), // if we have a sender_header, use it
                     None => {
                         // use a from header
@@ -783,15 +744,15 @@ impl EmailBuilder {
                                     // if it's an author group, use the first author
                                     Some(mailbox) => mailbox.address.clone(),
                                     // for an empty author group (the rarest of the rare cases)
-                                    None => return Err(Error::MissingFrom), // empty envelope sender
+                                    None => return Err(Error::Email(EmailError::MissingFrom)), // empty envelope sender
                                 },
                             },
                             // if we don't have a from header
-                            None => return Err(Error::MissingFrom), // empty envelope sender
+                            None => return Err(Error::Email(EmailError::MissingFrom)), // empty envelope sender
                         }
                     }
-                });
-                e
+                })?);
+                e.build()?
             }
         };
         // Add the collected addresses as mailbox-list all at once.
@@ -804,7 +765,7 @@ impl EmailBuilder {
             self.message
                 .add_header(Header::new_with_value("From".into(), self.from_header).unwrap());
         } else {
-            return Err(Error::MissingFrom);
+            return Err(Error::Email(EmailError::MissingFrom));
         }
         if !self.cc_header.is_empty() {
             self.message
@@ -845,20 +806,12 @@ impl EmailBuilder {
 }
 
 impl<'a> SendableEmail<'a, &'a [u8]> for Email {
-    fn to(&self) -> Vec<EmailAddress> {
-        self.envelope
-            .to
-            .iter()
-            .map(|x| EmailAddress::new(x.clone()))
-            .collect()
-    }
-
-    fn from(&self) -> EmailAddress {
-        EmailAddress::new(self.envelope.from.clone())
+    fn envelope(&self) -> Envelope {
+        self.envelope.clone()
     }
 
     fn message_id(&self) -> String {
-        format!("{}", self.message_id)
+        self.message_id.to_string()
     }
 
     fn message(&'a self) -> Box<&[u8]> {
@@ -975,14 +928,17 @@ mod test {
             .build()
             .unwrap();
 
-        assert_eq!(email.from().to_string(), "sender@localhost".to_string());
         assert_eq!(
-            email.to(),
+            email.envelope().from().unwrap().to_string(),
+            "sender@localhost".to_string()
+        );
+        assert_eq!(
+            email.envelope().to(),
             vec![
-                EmailAddress::new("user@localhost".to_string()),
-                EmailAddress::new("cc@localhost".to_string()),
-                EmailAddress::new("bcc@localhost".to_string()),
-            ]
+                EmailAddress::new("user@localhost".to_string()).unwrap(),
+                EmailAddress::new("cc@localhost".to_string()).unwrap(),
+                EmailAddress::new("bcc@localhost".to_string()).unwrap(),
+            ].as_slice()
         );
     }
 
diff --git a/website/content/sending-messages/file.md b/website/content/sending-messages/file.md
index 685301a..91dbdc0 100644
--- a/website/content/sending-messages/file.md
+++ b/website/content/sending-messages/file.md
@@ -16,17 +16,17 @@ extern crate lettre;
 use std::env::temp_dir;
 
 use lettre::file::FileEmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};
+use lettre::{SimpleSendableEmail, EmailTransport};
 
 fn main() {
     // Write to the local temp directory
     let mut sender = FileEmailTransport::new(temp_dir());
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new("user@localhost".to_string()),
-                    vec![EmailAddress::new("root@localhost".to_string())],
+                    "user@localhost".to_string(),
+                    &["root@localhost".to_string()],
                     "message_id".to_string(),
                     "Hello world".to_string(),
-                );
+                ).unwrap();
     
     let result = sender.send(&email);
     assert!(result.is_ok());
diff --git a/website/content/sending-messages/sendmail.md b/website/content/sending-messages/sendmail.md
index 85298ab..ae9ef4e 100644
--- a/website/content/sending-messages/sendmail.md
+++ b/website/content/sending-messages/sendmail.md
@@ -12,15 +12,15 @@ The sendmail transport sends the email using the local sendmail command.
 extern crate lettre;
 
 use lettre::sendmail::SendmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};
+use lettre::{SimpleSendableEmail, EmailTransport};
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new("user@localhost".to_string()),
-                    vec![EmailAddress::new("root@localhost".to_string())],
+                    "user@localhost".to_string(),
+                    &["root@localhost".to_string()],
                     "message_id".to_string(),
                     "Hello world".to_string(),
-                );
+                ).unwrap();
     
     let mut sender = SendmailTransport::new();
     let result = sender.send(&email);
diff --git a/website/content/sending-messages/smtp.md b/website/content/sending-messages/smtp.md
index 4bdd00b..c3d24b6 100644
--- a/website/content/sending-messages/smtp.md
+++ b/website/content/sending-messages/smtp.md
@@ -26,15 +26,15 @@ This is the most basic example of usage:
 ```rust,no_run
 extern crate lettre;
 
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress, SmtpTransport};
+use lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new("user@localhost".to_string()),
-                    vec![EmailAddress::new("root@localhost".to_string())],
+                    "user@localhost".to_string(),
+                    &["root@localhost".to_string()],
                     "message_id".to_string(),
                     "Hello world".to_string(),
-                );
+                ).unwrap();
     
     // Open a local connection on port 25
     let mut mailer =
@@ -52,17 +52,17 @@ fn main() {
 extern crate lettre;
 
 use lettre::smtp::authentication::{Credentials, Mechanism};
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress, SmtpTransport};
+use lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};
 use lettre::smtp::extension::ClientId;
 use lettre::smtp::ConnectionReuseParameters;
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new("user@localhost".to_string()),
-                    vec![EmailAddress::new("root@localhost".to_string())],
+                    "user@localhost".to_string(),
+                    &["root@localhost".to_string()],
                     "message_id".to_string(),
                     "Hello world".to_string(),
-                );
+                ).unwrap();
     
     // Connect to a remote server on a custom port
     let mut mailer = SmtpTransport::simple_builder("server.tld").unwrap()
@@ -109,10 +109,10 @@ fn main() {
     let _ = email_client.connect(&("localhost", SMTP_PORT), None);
     let _ = email_client.command(EhloCommand::new(ClientId::new("my_hostname".to_string())));
     let _ = email_client.command(
-                MailCommand::new(Some(EmailAddress::new("user@example.com".to_string())), vec![])
+                MailCommand::new(Some(EmailAddress::new("user@example.com".to_string()).unwrap()), vec![])
             );
     let _ = email_client.command(
-                RcptCommand::new(EmailAddress::new("user@example.org".to_string()), vec![])
+                RcptCommand::new(EmailAddress::new("user@example.org".to_string()).unwrap(), vec![])
             );
     let _ = email_client.command(DataCommand);
     let _ = email_client.message(Box::new("Test email".as_bytes()));
diff --git a/website/content/sending-messages/stub.md b/website/content/sending-messages/stub.md
index 8d2b533..3917e9e 100644
--- a/website/content/sending-messages/stub.md
+++ b/website/content/sending-messages/stub.md
@@ -13,15 +13,15 @@ testing purposes.
 extern crate lettre;
 
 use lettre::stub::StubEmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport, EmailAddress};
+use lettre::{SimpleSendableEmail, EmailTransport};
 
 fn main() {
     let email = SimpleSendableEmail::new(
-                    EmailAddress::new("user@localhost".to_string()),
-                    vec![EmailAddress::new("root@localhost".to_string())],
+                    "user@localhost".to_string(),
+                    &["root@localhost".to_string()],
                     "message_id".to_string(),
                     "Hello world".to_string(),
-                );
+                ).unwrap();
     
     let mut sender = StubEmailTransport::new_positive();
     let result = sender.send(&email);