Spam building up in sendmail's /var/spool/mqueue folder

Question

the server we maintain has recently been running out of memory - this was found to be due to many sendmail processes. Looking at /var/spool/mqueue there is approx 500 emails/30 seconds being put in there when the sendmail service is started. These contain rejections from the yahoo mailserver 'due to user complaints' - so it seems as though a user on this network has given out their email details and thus crippled the server with spam messages. Is there any way to prevent these messages queuing up so I can restore normal mail operation?

Thanks

Answer 1

Please do yourself, and the world, a favour and replace Sendmail with something easier to configure and maintain, like Exim or Postfix. I would normally vote down answers that said "use a different product", but in the case of Sendmail, I think it's worth the risk. Sendmail is very complex to configure compared to modern MTAs and should only be used if you have an existing complex Sendmail infrastructure and you have considerable Sendmail experience.

Having said that, your best bet is to work out what emails Yahoo are rejecting and reject them yourself before they get on your queue. You may also want to figure out why Yahoo are rejecting them and see if there's any way you can get Yahoo to unblock you. Perhaps they think you're spammers. Most last email companies provide a way for you to tell Yahoo that you're not really spammers and that you've fixed any problems that caused them to block you.