spam has been a great problem now a days. If you use qmail u must experiencing some irritating double bounce problem.
here is the little tricks to tune your qmail…

create a dummy mail address like dump.mail@yourdomain.com

Then edit .qmail file of the address that u have created that is dump.mail
remove ./Maildir
and add the following
|exit 0
then add the dump.mail@yourdomain.com to the /var/qmail/control/doublebouceto
Ohhhhhhhh… relief!! for a while…..