lifted from here
Qmail Log Location in Plesk:
/usr/local/psa/var/log/maillog
Ignore Mail to unkown user instead of bouncing:
One domain at a time:
edit /var/qmail/mailnames/<domain.goes.here.com>/.qmail-default and replace its contents with: |true
to change for all domains:
find /var/qmail/mailnames/ | grep .qmail-default | xargs replace “|bouncesaying ‘This address no longer accepts mail.’” ‘|/bin/true‘ –
