qmail-smtpd-chkusr is a patch for qmail-smtpd (with vpopmail 4.9.x) and
permits rejecting non existing users/aliases/mailing-lists in the smtp
acceptance phase.
I've just updaded this patch, with the following changes:
- changed the error code emission (550 instead of 553)
- added check for BOUNCE_MAIL flag
This patch is freely available at
http://www.interazioni.it/qmail
