qmail
Suppose you would like to send a copy of an incoming email to another account while the email still goes to the original account. You can do this by modifying the .qmail file of the original recipient and adding an entry that looks like the following:
On a Plesk server, a full .qmail file with the above changes looks like this:
&user@domain.com
| /usr/bin/deliverquota ./Maildir
Keep in mind that if you do this on a Plesk server, these changes will be overwritten with mchk or upgrades so you will have to take measures to deal with this. I set the files immutable so they can't be changed by Plesk. This causes its own problems so you will have to decide if it is worth it.
I may be wrong here, but I believe the default queue lifetime for a message sitting in the qmail queue is 7 days. To me, that's entirely too long to wait to deliver a defunct message considering most of them are probably SPAM bounces anyway.
Here is how to shorten the lifetime.
Change to the qmail control directory, assuming you use default locations on your server.
Set the timeout to the number of seconds you want the message to remain in the queue. This is done in the queuelifetime file. This file doesn't normally exist by default. I'll use 24 hours (86,400 seconds) as an example.
Restart qmail.
That's it. Messages that don't get delivered in 24 hours will be gone.
First, copy the smtp_psa file.
Edit the newly copied file and replace the first line. Replace 'service smtp' with 'service submission'
Restart xinetd.d
Check that port 587 is listening on the server
qmHandle is a handy tool to aid in administering the queue on qmail enabled servers.
Get and install qmHandle
Get and replace existing qmHandle
Usage is simple. After installing, just issue qmHandle without any arguments and you will be presented with a list of options.