feat(transport-smtp): Use hostname as clientid when available

lettre/Cargo.toml

@@ -21,6 +21,7 @@ bufstream = { version = "^0.1", optional = true }
 native-tls = { version = "^0.1", optional = true }
 base64 = { version = "^0.8", optional = true }
 hex = { version = "^0.3", optional = true }
+hostname = { version = "^0.1", optional = true }
 rust-crypto = { version = "^0.2", optional = true }
 serde = { version = "^1.0", optional = true }
 serde_json = { version = "^1.0", optional = true }
@@ -35,7 +36,7 @@ unstable = []
 serde-impls = ["serde", "serde_derive"]
 file-transport = ["serde-impls", "serde_json"]
 crammd5-auth = ["rust-crypto", "hex"]
-smtp-transport = ["bufstream", "native-tls", "base64", "nom"]
+smtp-transport = ["bufstream", "native-tls", "base64", "nom", "hostname"]
 sendmail-transport = []
 
 [[example]]

lettre/src/lib.rs

@@ -19,6 +19,8 @@ extern crate base64;
 extern crate bufstream;
 #[cfg(feature = "smtp-transport")]
 extern crate native_tls;
+#[cfg(feature = "smtp-transport")]
+extern crate hostname;
 #[cfg(feature = "file-transport")]
 extern crate serde_json;
 #[cfg(feature = "serde-impls")]

lettre/src/smtp/mod.rs

@@ -106,6 +106,7 @@
 use EmailTransport;
 use SendableEmail;
 use native_tls::TlsConnector;
+use hostname::get_hostname;
 use smtp::authentication::{Credentials, DEFAULT_ENCRYPTED_MECHANISMS,
                            DEFAULT_UNENCRYPTED_MECHANISMS, Mechanism};
 use smtp::client::Client;
@@ -224,7 +225,7 @@ impl SmtpTransportBuilder {
                     smtp_utf8: false,
                     credentials: None,
                     connection_reuse: ConnectionReuseParameters::NoReuse,
-                    hello_name: ClientId::Domain("localhost".to_string()),
+                    hello_name: ClientId::Domain(get_hostname().unwrap_or("localhost".to_string())),
                     authentication_mechanism: None,
                     timeout: Some(Duration::new(60, 0)),
                 })