On Mon, 09 May 2011 11:23:16 -0400, Jesse Rosenthal <jrosenthal@jhu.edu> wrote: > 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." Apologies -- I realize now you were talking about threads and not messages, so I can't defer to RFCs. I still agree with the others, and about how python users would deal with it. But I see your point better now. Sorry to clutter.