To be sure your window stays there, and to avoid blocking other actions in .maildelivery , run rcvxterm in the background as shown above. Use cat to copy the message into a temporary file. The script is below. If you haven't installed a shell script before, there's help in the Section Writing Shell Scripts for MH . A handler can read your system mailbox file directly, usually with inc .
Most handlers are probably shell or perl scripts.
A script can be run by hand when you type its name at a shell prompt, or your computer can run it automatically with at or cron . One automatic handler is the autoinc shell script . After you write a script like autoinc , add an entry to your personal crontab file or start an at job to run your script whenever you want. It's probably a good idea to run it late at night, if you can. The load on the system might be less then.