Chkuser 2.0

This is the home of chkuser, the patch used with qmail and vpopmail in order to check at SMTP level the existence of recipients, avoiding useless bouncings and saving bandwith.

For informations and support , see the chkuser 2.0 section.

Previous versions of chkuser, named chkusr, are still available here.


For general support see the support page.

Breaking News:

Tuesday 02 March 2010

xn-- / puny code

If you use chkuser with format checking enabled, you may face problems with xn-- domains (i.e. domains written with puny code notation).