Part 2 in my ongoing smartphone adventures!
Just in case you wanted "Direct Push Technology" and you don't run Exchange, then your options are these (none of them work, if you want the summary):
1. Run using T-Mobile's hosted service, which under the covers converts IMAP/SSL to something like POP3. This service sends you silent SMSes which trigger the Windows Mobile client to sync. (You're not charged for the SMSes.) But it is so insecure and you don't share deletes and unread flags with your IMAP server. Boo hiss.
2. Run Flexmail, which does IMAP IDLE against IMAP! (Hope?) Except it doesn't work with SSL (so close but...no). The UI looks pretty, but it doesn't have the basics, like when you're viewing a message, the left and right arrow keys do...nothing. You go back to the message list and pick another message to read. Works great with GMail/Pop3/SSL though.
3. Get your hopes up that vgsmail will work with your phone, to find out that it doesn't.
4. Run the built-in Messaging app with its minimum polling rate of once per 15 minutes, bad tendency to download way too much information on sync, bugs with deleting files on IMAP servers, and live with it.
How much does an Exchange license cost again? Oh wait, that's what they want me to say.