in reply to Re^2: Exim, for the love of Perl
in thread Which MTA is best to use with Perl....
- I assume your SMTP solution is going to deliver all mail to a "smart host", and isn't going to do MX resolving itself, and deliver the mail to one of the servers returned. In that case, if you get a "relaying denied" error, you have a serious problem - it basically means all you may be able to do send mail to local users. Your error message should have been "this solution is never ever going to work".
- If the user gets a "connection refused" message, he'll be pissed. He doesn't want a "connection refused" message from an MTA. He wants the MTA to queue the mail and retry again. That's the task of the MTA - not the task of the user. This problem was solved more than 30 years ago.
- If you just fill in a correct return address errors, not only the error message will be send to the user, the mail as sent will be returned as well, even if there's a problem (like 'relaying denied') further down the line.