The first place you should look for problems in Zimbra is
bugzilla, in this case there are two bugs associated with that phone:
Bug 38854 – Support for HTC Magic (Running Android OS with ActiveSync support) Bug 35421 – Red face HTC TYTN II push mail problem with zimbra not with exchange 2007
You should vote on any bug reports (or RFEs) that you have an interest in getting fixed. As you're both NE customer then you should also open a support case and reference the bug report that matches your problem (or file a new report) and get the case attached to the relevant bug report. While it's a good idea to ask in the ofurms if anyone else has the problem the most expedient is to file bug reports and open support cases, that will get the attention of developers.
So we don't have to keep asking, could you both update your forum profiles with the output of the following: