For the past 48 hours, I've been dealing with a Sendmail server that was shutting down frequently with a load average above 13. The server's getting flooded constantly with spam attempts to non-existent users on more than 100 domains. I've set up Sendmail to use a virtusertable that rejects every non-valid email address with a "user unknown" error. This is helpful, but Sendmail still has to take the time to reject each spam attempt. Since all but six domains on the server don't receive any mail at all, I wanted ... read more