Added setting for SMTP hello command.

src/config.rs

@@ -65,6 +65,7 @@ pub struct Mailing {
     from: String,
     path: Option<String>,
     server: Option<String>,
+    hello_name: Option<String>,
     port: Option<u16>,
     user: Option<String>,
     password: Option<String>,
@@ -86,6 +87,9 @@ impl Mailing {
     pub fn server(&self) -> &Option<String> {
         &self.server
     }
+    pub fn hello_name(&self) -> &Option<String> {
+        &self.hello_name
+    }
     pub fn port(&self) -> Option<u16> {
         self.port
     }