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Qmail Chkuser Patch


The original qmail-smtpd accepts by default all messages, checking later for the existence of recipients. So, if the message is delivered to not existing recipients, a lot of additional system work and network traffic are generated, with multiple expensive bouncing if the sender is a fake one.

chkuser has been developed with the goal to improve the acceptance SMTP phase of qmail-smtpd. qmail-smtpd patched with chkuser may check the existence of e-mail recipients immediately in the SMTP acceptance phase of a message and rejects instantly all messages not directed to existing users, avoiding additional traffic, work and messages bounced more times.

These goals are achieved enquiring the existing vpopmail archives (each format is supported: cdb, MySQL, LDAP, etc.) by using standard vpopmail calls, or using customized chkuser routines.


Tony has done a great job of documenting all the extremely powerful features of chkuser 2.0 on his chkuser settings page. I recommend using the quota checking option.

Last modified on 4/28/05.