diff --git a/lettre/Cargo.toml b/lettre/Cargo.toml
index 446bb1a..5a9823a 100644
--- a/lettre/Cargo.toml
+++ b/lettre/Cargo.toml
@@ -15,10 +15,10 @@ keywords = ["email", "smtp", "mailer"]
 travis-ci = { repository = "lettre/lettre" }
 
 [dependencies]
-bufstream = "^0.1"
 log = "^0.3"
-native-tls = "^0.1"
-base64 = "^0.6"
+bufstream = { version = "^0.1", optional = true }
+native-tls = { version = "^0.1", optional = true }
+base64 = { version = "^0.6", optional = true }
 hex = { version = "^0.2", optional = true }
 rust-crypto = { version = "^0.2", optional = true }
 serde = { version = "^1.0", optional = true }
@@ -29,8 +29,14 @@ serde_derive = { version = "^1.0", optional = true }
 env_logger = "^0.4"
 
 [features]
-default = ["file-transport", "crammd5-auth"]
+default = ["file-transport", "crammd5-auth", "smtp-transport", "sendmail-transport"]
 unstable = []
 serde-impls = ["serde", "serde_derive"]
 file-transport = ["serde-impls", "serde_json"]
-crammd5-auth = ["rust-crypto", "hex"]
\ No newline at end of file
+crammd5-auth = ["rust-crypto", "hex"]
+smtp-transport = ["bufstream", "native-tls", "base64"]
+sendmail-transport = []
+
+[[example]]
+name = "smtp"
+required-features = ["smtp-transport"]
diff --git a/lettre/src/lib.rs b/lettre/src/lib.rs
index cc9ecd6..89d7fc9 100644
--- a/lettre/src/lib.rs
+++ b/lettre/src/lib.rs
@@ -8,12 +8,15 @@
 
 #[macro_use]
 extern crate log;
-extern crate base64;
 #[cfg(feature = "crammd5-auth")]
 extern crate hex;
 #[cfg(feature = "crammd5-auth")]
 extern crate crypto;
+#[cfg(feature = "smtp-transport")]
+extern crate base64;
+#[cfg(feature = "smtp-transport")]
 extern crate bufstream;
+#[cfg(feature = "smtp-transport")]
 extern crate native_tls;
 #[cfg(feature = "file-transport")]
 extern crate serde_json;
@@ -21,7 +24,9 @@ extern crate serde_json;
 #[macro_use]
 extern crate serde_derive;
 
+#[cfg(feature = "smtp-transport")]
 pub mod smtp;
+#[cfg(feature = "sendmail-transport")]
 pub mod sendmail;
 pub mod stub;
 #[cfg(feature = "file-transport")]
@@ -29,8 +34,11 @@ pub mod file;
 
 #[cfg(feature = "file-transport")]
 pub use file::FileEmailTransport;
+#[cfg(feature = "sendmail-transport")]
 pub use sendmail::SendmailTransport;
+#[cfg(feature = "smtp-transport")]
 pub use smtp::{SmtpTransport, ClientSecurity};
+#[cfg(feature = "smtp-transport")]
 pub use smtp::client::net::ClientTlsParameters;
 use std::fmt::{self, Display, Formatter};
 use std::io::Read;
diff --git a/lettre/tests/transport_file.rs b/lettre/tests/transport_file.rs
index 97dc5da..ad8841e 100644
--- a/lettre/tests/transport_file.rs
+++ b/lettre/tests/transport_file.rs
@@ -5,7 +5,6 @@ extern crate lettre;
 mod test {
 
     use lettre::{EmailAddress, EmailTransport, SendableEmail, SimpleSendableEmail};
-    #[cfg(feature = "file-transport")]
     use lettre::file::FileEmailTransport;
     use std::env::temp_dir;
     use std::fs::File;
@@ -13,7 +12,6 @@ mod test {
     use std::io::Read;
 
     #[test]
-    #[cfg(feature = "file-transport")]
     fn file_transport() {
         let mut sender = FileEmailTransport::new(temp_dir());
         let email = SimpleSendableEmail::new(
@@ -39,4 +37,5 @@ mod test {
 
         remove_file(file).unwrap();
     }
+
 }
diff --git a/lettre/tests/transport_sendmail.rs b/lettre/tests/transport_sendmail.rs
index ebdb906..8c7cc80 100644
--- a/lettre/tests/transport_sendmail.rs
+++ b/lettre/tests/transport_sendmail.rs
@@ -1,19 +1,25 @@
 extern crate lettre;
 
-use lettre::{EmailAddress, EmailTransport, SimpleSendableEmail};
-use lettre::sendmail::SendmailTransport;
+#[cfg(test)]
+#[cfg(feature = "sendmail-transport")]
+mod test {
 
-#[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())],
-        "sendmail_id".to_string(),
-        "Hello sendmail".to_string(),
-    );
+    use lettre::{EmailAddress, 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())],
+            "sendmail_id".to_string(),
+            "Hello sendmail".to_string(),
+        );
+
+        let result = sender.send(&email);
+        println!("{:?}", result);
+        assert!(result.is_ok());
+    }
 
-    let result = sender.send(&email);
-    println!("{:?}", result);
-    assert!(result.is_ok());
 }
diff --git a/lettre/tests/transport_smtp.rs b/lettre/tests/transport_smtp.rs
index 9826409..236b382 100644
--- a/lettre/tests/transport_smtp.rs
+++ b/lettre/tests/transport_smtp.rs
@@ -1,19 +1,24 @@
 extern crate lettre;
 
-use lettre::{ClientSecurity, EmailAddress, EmailTransport, SimpleSendableEmail, SmtpTransport};
+#[cfg(test)]
+#[cfg(feature = "smtp-transport")]
+mod test {
 
-#[test]
-fn smtp_transport_simple() {
-    let mut sender = SmtpTransport::builder("127.0.0.1:2525", ClientSecurity::None)
-        .unwrap()
-        .build();
-    let email = SimpleSendableEmail::new(
-        EmailAddress::new("user@localhost".to_string()),
-        vec![EmailAddress::new("root@localhost".to_string())],
-        "smtp_id".to_string(),
-        "Hello smtp".to_string(),
-    );
+    use lettre::{ClientSecurity, EmailAddress, EmailTransport, SimpleSendableEmail, SmtpTransport};
+
+    #[test]
+    fn smtp_transport_simple() {
+        let mut sender = SmtpTransport::builder("127.0.0.1:2525", ClientSecurity::None)
+            .unwrap()
+            .build();
+        let email = SimpleSendableEmail::new(
+            EmailAddress::new("user@localhost".to_string()),
+            vec![EmailAddress::new("root@localhost".to_string())],
+            "smtp_id".to_string(),
+            "Hello smtp".to_string(),
+        );
+
+        sender.send(&email).unwrap();
+    }
 
-    let result = sender.send(&email);
-    assert!(result.is_ok());
 }