Have you installed Microsoft’s SMTP Patch?
If so, did you have an issue? If not, be aware that there might be an issue where it could delete your email Accounts as it did with Mike Temporale over at Mobile Jaw. The patch was released to fix an issue with sending email on your Windows Mobile 6.1 device but Mike has 3 issues that you might want to read about before you install the patch.
More at: Have you installed Microsoft’s SMTP Patch? | Mobility Site