My secondary mail server (that runs qmail) had a load of email queued up today that I needed to flush. Googling comes back with people saying run qmail with daemontools then you can use on of the nice qmailctl scripts to do a 'doqueue'. Needless to say I'm not running with daemontools (my primary is), it's just a secondary server that does *nothing* else and I wanted to keep it nice and simple.
Anyway, I finally found out that sending an ALRM signal to qmail-send works.
Specifically, this worked:
[code] bash:# kill -ALRM (qmail-send PID)[/code]