If you want to adjust how long e-mails will spend in the qmail queue before they're bounced, simple set the queuelifetime:
# echo "432000" > /var/qmail/control/queuelifetime
# /etc/init.d/qmail restart
The above example is for 5 days (qmail needs the time length in seconds). Just take the days and multiply by 86,400 seconds to get your result.
