Happy New Year (almost)!
Archives show me that this topic went around a while back but I did not
find a complete answer. It's not really a Mailman bug, but a Mailman choice
between correct options.
When the Subject is folded into more than 1 line, Mailman inserts
whitespace in the form of a TAB character, at the start of the continuation
lines. Outlook, when unfolding, removes the CR LF but leaves whatever
whitespace is there, in this case a TAB, so people tell me it looks ugly.
I noticed that in Mailman/Handlers/CookHeaders.py, we go out of our way to
change email.header's continuation_ws from the default of one space to be
one tab. Both are correct, since the standard just says whitespace, but if
we used one space it would trick Outlook into doing the right thing.
Why the tab? CookHeaders.py gets pretty hairy so I feel like I'm missing
Columbia University Information Technology