Little refactoring

src/transport/smtp/response.rs

@@ -184,11 +184,7 @@ impl ResponseParser {
 
         if line.len() > 4 {
             self.message.push(line[4..].to_string());
-            if line.as_bytes()[3] == '-' as u8 {
-                Ok(true)
-            } else {
-                Ok(false)
-            }
+            Ok(line.as_bytes()[3] == '-' as u8)
         } else {
             Ok(false)
         }

src/transport/stub/mod.rs

@@ -6,7 +6,7 @@ use transport::smtp::response::{Category, Code, Response, Severity};
 use transport::EmailTransport;
 use email::SendableEmail;
 
-/// This transport does nothing exept logging the message enveloppe
+/// This transport does nothing except logging the message enveloppe
 pub struct StubEmailTransport;
 
 impl EmailTransport for StubEmailTransport {