On Mon, 09 May 2011 17:13:10 +0200, Anton Khirnov <anton at khirnov.net> wrote: > But those aren't message headers, those are thread properties. And I'd > argue that a thread always has authors and a subject (possibly empty).
The RFC says yes on the author, no on the subject. The only things guaranteed are "From:" and originating timestamp. So I'm not sure why subject should be guaranteed a string result and not, say, "Cc." My sense is that Python users are prety good with testing against None, especially since (not "") == (not ) == (not None) == True. This change seems like it would end up producing more inconsistencies with the way you deal with headers, by producing special cases. --Jesse