It would be nice if _handle_message in roundup/mailgw.py was split up
into many functions instead of one large one. I imagine it would have
benefits for maintainabilty, but...

I have a custom mailgw script that inherits from MailGW, and I am
currenly defining my own _handle_message to change parts of how emails
are handled as they come in. For the most part it is identical to the
original _handle_message, but is does contain a few small alterations.

I am basically duplicating ~600 lines of code just the change a few
small parts of it. If _handle_message was split up into many functions,
it could override only the ones I want to change, without having to
duplicate large chunks of code (and help improve compatability with
future versions).