Ok I'll give that a try... Currently I have an operational ISPConfig with Roundcube and I wanted to just add Horde to it. So far the test system (nothing on it) worked so I'll post back if its working and what I did.
As for the Active Sync email, it appears to be coming in Horde 5?? http://wiki.horde.org/ActiveSync
So do you setup for example on the iPhone 2 accounts, 1 is Exchange with Contacts and Calendar enabled and the other is an IMAP account for the Email??
The ultimate system then would be ISPConfig and Horde with FULL activesync abilities. I wish that more people with knowledge could help the guys out at horde.org - Just saying