Fix typo and add Subject support

lib/msf/core/exploit/smtp_deliver.rb

@@ -142,13 +142,18 @@ module Exploit::Remote::SMTPDeliver
     raw_send_recv("RCPT TO: <#{datastore['MAILTO']}>\r\n", nsock)
 
     # If the user supplied a Date field, use that, else use the current
-    # DateTime in the propper RFC2822 format.
+    # DateTime in the proper RFC2822 format.
     if datastore['DATE'].present?
       raw_send_recv("Date: #{datastore['DATE']}\r\n", nsock)
     else
       raw_send_recv("Date: #{DateTime.now.rfc2822}\r\n", nsock)
     end
 
+    # If the user supplied a Subject field, use that
+    if datastore['SUBJECT'].present?
+      raw_send_recv("Subject: #{datastore['SUBJECT']}\r\n", nsock)
+    end
+
     resp = raw_send_recv("DATA\r\n", nsock)
 
     # Avoid sending tons of data and killing the connection if the server