Mark Sapiro wrote:
Here's the result: In applying header_filter_rules, it looks like the entire set of headers is being treated as a single multiline string.
That is correct.
For reasons I don't entirely understand (remember I'm not a python expert), "^" and "$" are not matching the beginning and end of individual lines of a multiline string, even though I interpreted http://www.python.org/doc/current/lib/matching-searching.html to say that they should, and a colleague who's very familiar with Python also thought they should.
It works for me.
I suspect you have an old Mailman version. Prior to Mailman 2.1.7, the regular expression search was not multiline and therefore '^' and '$' would only match the beginning and end respectively of the string of all the headers.
I have updated FAQs 3.32 (again) and 3.51 to note the version dependence.