via Mailman-users writes:
I have a mailing list that, due to specific circumstances, has a requirement to allow messages from a user that sends messages with no subject.
Do you mean "any user who sends a message with no subject", or are there specific users who do this? If there is one such user (or a handful), and you trust that user not to abuse the privilege, you can directly pre-approve that user from Users menu in the list configuration (see Mark's post for details). This also works if there is no Subject field at all!
If you don't know who might post with no subject (or there are annoyingly many, especially if some are less than clueful), you could use the header match:
I also added header filters to immediately accept the message, but they still get held. Specifically, the rules I defined are: [...]
Those were all incorrect. What you want is
Header, Pattern, Action
subject, ^\s*([[{(]?no[_ ]subject[]})]?)?\s*$, Accept Immediately
I believe the surrounding whitespace is stripped, so the "\s*" are unnecessary but do no harm since they match 0 spaces. However this has two potential flaws: it doesn't work if there is no Subject field at all, and it allows anyone to bypass all of Mailman's checks.
Finally, there is the "pre-approved" mechanism. It's a little bit complicated because it requires setting a moderator password, which has to be done using the Python interpreter; there's no option in Postorius. It also requires a small bit of clue from the poster to add the password to the post, preferably in the header (but it can also be the first line). In either case the password is removed before distribution. For details, see
https://docs.mailman3.org/projects/mailman/en/latest/src/mailman/rules/docs/...
Is there a better way to bypass this rule?
Each of the three approaches has advantages and disadvantages, so you'll have to decide.
-- GNU Mailman consultant (installation, migration, customization) Sirus Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan