qmail-smtpd does not know if a user exists. Lots of resources are wasted by scanning mail for spam and viruses for addresses that do not exist anyway.
A replacement smtpd written in Perl could use this module to quickly verify that a local email address is (probably) actually in use.
This module comes with a daemon program called qmail-deliverabled and a module called Qmail::Deliverable::Client that copies the entire public interface, but queries the daemon. Typically, the daemon runs as the root user, and the client is used by the unprivileged smtpd.
INSTALLATION
To install this module type the following:
perl Makefile.PL
make
make test
make install
DEPENDENCIES
This module requires a functional qmail installation in its standard location, /var/qmail.
COPYRIGHT AND LICENCE
Put the correct copyright and licence information here.
Copyright (C) 2007 by Juerd Waalboer
Released into the public domain, without warranty or guarantee of any kind. Use at your own risk.