As of 7/26 there’s a new version (2.9.25.3319) of my favorite free Pocket PC IMAP client, QMail3. It now suposedly supports WM5, although I’m running WM5 on both of my devices and I’ve never really had a problem with it. There’s also a set of updated SSL modules (which you can download from here, down at the bottom). Matter of fact, if you look at that page, you’ll see that you can download not only what he calls the “snapshot” (aka stable build) but the nightlies, too.
Download links, all for ARM processors: