For about a week now, our mail server has been getting flooded with email address to non-existent recipients.
The emails are coming in from all over and are mostly a bounce from a MAILER-DAEMON addressed to firstname.lastname@example.org
We have Qmail and because Qmail does not have a mechanism to check for valid users, it happily accepts to mail. This is a major problem because now the queue is reaching numbers in the hundreds of thousands and most of the email is junk. This puts a burden on the resources because the legitimate email is not being delivered on time
We have created a few immediate solutions by installing scripts to safely remove the junk mail from the queue and also have installed a mail gateway. This is however not stopping a the email@example.com
emails from being delivered to our server.
Any suggestions, directions or ideas would be greatly appreciated.