By default Pocket PCs (like the 4155) sync with Outlook, but you can use a syncing software besides Activesync (similar to hotsync for Palm). For instance Intellisync allows a Pocket PC to sync with:
Microsoft Outlook 97/98/2000/2002/2003
Microsoft Outlook Express 5.0/6.0
Lotus Notes 4.5/4.6/5.0/6.0/6.5/6.5.1
ACT! 4.02/2000/5.0/6.0
Lotus Organizer 5.0/6.0
Palm Desktop 4.01/4.1
or Novell Groupwise!
Intellisync :lol: