When the SMTP session ends with an error such as the aforementioned:

[1361] Dec 01 11:39:08 [Debug] SMTP : Closed connection: "550 5.7.1 Rejected 212.152.85.98 listed as spam source at http://www.spamhaus.org

Would it be possible to show the exact text of the error message to the user and not just a generic "could not connect to server" message? Or is there a setting somewhere which can enable this function?