This can be rather involved, but I've written some hints here . Fire it up and try a test message. If everything's set up properly, simply running the fetchmail command with no arguments will cause fetchmail to download mail off the remote site and trestlemail to redistribute it. If this worked, you're in good shape. If not, maybe the next section on Debugging will help.
Any errors here go into to the fetchmail log file.
Any stdout or stderr output from either Perl or Trestlemail also go into the fetchmail log file. The fetchmail log file is specified in fetchmailrc. When Trestlemail starts up, it reads the trestlemailrc file to tell it how to distribute the message. If the message is destined for a mailing list, Trestlemail removes extraneous headers, marks the message as bulk, reads the mailing list file, and sends a copy of the message to every subscriber to the list. Its task finished, Trestlemail exits and waits for Fetchmail to start it up again to deliver the next message.