Oi, complicated situation here.  I'd add a comment along the lines of the following:

"""
XXX supportsServerFolders is a bit of a misnomer in this case; we are doing this to make the unit tests happy.  ActiveSync does not support appending messages via the ActiveSync protocol, but it supports server folders.  POP3 doesn't support anything.  Changing this will result in some hassle we don't want to deal with right now.
"""

Or you can try and deal with this at a fancier level.  It makes me tired just thinking about it right now, so your call.