On Mailman-Users, Mark Sapiro writes:
Further, in the ban_list (and many other places in Mailman) if an address is intended to be a regular expression pattern, it must begin with '^', so you really want
^.*@domain\.com$
to match any_address@domain.com.
I hope we haven't propagated this rather user-unfriendly interface (the convention of accepting both regexps and literals, distinguishing by "^" in column 0) to Mailman 3. Even as a Python programmer, I find Mark's post somewhat confusing: I would design filters using re.search, so that the above would actually be equivalent as a Python regular expression to r"@domain\.com$". OTOH, if the implementation uses re.match, the "^" is redundant, so I have a "say what?!" event.
If we have, I propose changing it to
Ban these addresses, one entry per line: [ ]
[ ] Entries are regular expressions.or something like that. We also ought to have a "Python features for Mailman administrators" section of the FAQ, starting with "what is a regular expression", and giving examples of how to accomplish common tasks like banning a whole domain with regular expressions. Typical regexp FAQs are hard for non-programmers (and even beginning programmers) to grasp.
I don't have time to actually work on these now, but if there's uptake on the suggestion ("let's think about it" at +0 or above :-) I'll file issues.