Can Procmail be configured to get rid of mail after it is passed to a script?

Question

I have Postfix installed and configured to pass mail to Procmail. I have Procmail configured to pass the email to a Python script. I also notice that Procmail is placing a copy of the same email into a file at /var/spool/mail/<username>. I don't want a copy of the message to be retained there or anywhere on the server. Is there a way to configure Procmail to drop the message after it is sent to the Python script?

In my .procmailrc configured like so:

:0Wc:
| env python3 /home/user/python/script.py
:0
* ^From:.*@.*
/dev/null

This however does not work. The message still ends up /var/spool/mail/<username>.

Answer 1

This is exactly how Procmail operates out of the box. Recipes are executed sequentially until a delivering action is taken, or until we run out of recipes, and deliver to $DEFAULT. Writing to a mailbox, piping to a command, or forwarding to a different recipient are all delivering actions.

However, your first recipe has a c flag, which explicitly disables this behavior, and causes another delivery to be attempted even after this action completes.

In so many words, take out the c flag (and probably the second colon, too; or name an explicit lock file after it).

The old (not so) mini-FAQ has a section about locking which coincidentally also has a passage about your main question, and a discussion of "deliveredness".