Quoting ng0 (2017-01-28 18:21:10)
> Is it possible to apply tags to message-ids, something similar to
>
> notmuch tag -inbox +python +python::list -- python-list-request@python.org OR python-list@python.org OR id:*python-list@python.org

If notmuch search can find it notmuch tag should be able to tag it. So
you can try notmuch search first (maybe have a look at the man page
notmuch-search and check --output=files).

> I'm also open to other solutions (the untagged messages share at
> least a common folder structure
> "/home/user/mail.python.org/.lists-python-1999-March/" as an
> example), this runs in a script anyway.

And check notmuch-search-terms(1) to see if the folder: or path: search
terms can help you.