Great question!
I happen to have some stuff written up from personal experience for other clients. It's pasted below:
PLESK Installation requires full administrator access.
Here is how to set it up:
SMTP: a setting of hostname "localhost" with no additional authorization should be fine to send email through ListMail.
----
Email Aliases:
Be sure that the account bounce@site.com does not exist in the Plesk control panel as a mailbox or email will not be delivered to the CGI script.
Set up bounce.cgi in your site's cgi-bin, modifying it to contain your ListMail URL and CHMOD it to 755.
cd /var/qmail/mailnames/site.com
make a file named .qmail-bounce
In it have the following:
|/home/httpd/vhosts/site.com/cgi-bin/bounce.cgi
Also, run the following command, which is necessary after Plesk 6:
chmod 755 /home/httpd/vhosts/site.com/cgi-bin
----
Cron task:
The task should be as follows, set up through either the Plesk control panel or via the commandline as the administrator:
(example to run at 12:15 am)
15 0 * * * /usr/bin/wget -O /dev/null -T 0
http://site.com/mail/dailymail.php?pw=YourDailyPass 1> /dev/null 2> /dev/null
Double check your dailymail password in ListMail (copy & paste) and enable "send dailymail report to admin". You should then start receiving notifications when the task is run.
----
One further modification will allow you to send up to a million emails per day per server.
use the following command to create a file in your qmail control directory containing the number "400".
echo "400" > /var/qmail/control/concurrencyremote
Then, restart qmail
/etc/init.d/qmail restart
This allows up to 400 outbound email processes at once, as opposed to the default of 10 or 20.
You should achieve 25-50 emails per second with this setting.
You can also improve inbound mail speed (not as important) like this:
echo "100" > /var/qmail/control/concurrencylocal
Again, restart qmail
/etc/init.d/qmail restart