> The "standard" chkuser patch that vpopmail uses (see Bill > Shupp's update to the original: > http://www.shupp.org/patches/chkuser-0.6.mysql.patch) has > some rather nasty behaviours. > > If for some reason your mysql server is unavailable (load has > shot so high that mysql can't return a prompt reply, you're > upgrading mysql, taking db down for maintenance, etc.) the > chkusr patch will start telling remote smtp clients that the > user doesn't exist. This is not good; you never want to send > a 550 on a user that really does exist; people get upset when > things bounce, and mailing lists start looking at auto-removal.
That explains a lot. I thought the chkuser patch was awesome until I started seeing 550's bouncing to customers for email addresses that aren't actually 550. I'll be happy when the new patch comes about that fixes this issue. -Russell
