I forked PHPMailer and added functionality to log SMTP remote server responses (particularly useful when you're trying to see if mail was or was not delivered i.e., "When someone says: "I didn't get the email from your website" you can tell them: "That's because your mailbox was full at the time.").

Question for the maintainers: is this something that you would want to re-incorporate (pull) back into the trunk? Looking for guidance on how to contribute useful things to the PHPMailer project.