I have a site where users register for an account. I have an internal communication system, that sends them an email when they get a private message. I dont force people to confirm their email, so naturally, many enter a fake address.
When they get a PM, it tries to send them an email, but obviously fails, so it keeps retrying and retrying. After a few weeks, the retry queue gets quite big, and it affects server performance (I also dont wanna get blacklisted for all these attempts).
What can I do to solve this issue (other than force people to confirm their email upon registration).
If you don't want to force people to confirm their email because if something goes wrong, they can't access their login straight away, why not do something like this:
If they haven't confirmed their E-Mail, don't send PMs, but show them when they are logged in instead. Remind them to confirm their E-Mail.
If they have confirmed their E-mail, send them out.
But anyway, your scenario sounds like a server misconfiguration. Why would a mail server keep re-sending mails that it got a "not deliverable" message for? As far as I know, re-sending mails only occurs when the receiving host was not reachable for technical reasons.