WM 6.1 sending POP/IMAP email fix released by Microsoft
Microsoft has released for download a patch to fix an email sending problem specific to Windows Mobile 6.1 where you can unexpectedly loose the ability to send out email messages. This problem is more clearly defined in the
Microsoft KB article KB958639, where you could find more details about the problem.
There is also a little bit of controversy surrounding the cause of this problem. With Windows Mobile 6.1, Microsoft decided to add a feature in the email system which enable the mobile operator or OEM to define an alternate SMTP server name, in case the user-defined server name fails. more on this issue is found on the Pocket PC Thoughts forum.
You can download the patch from the Microsoft Download website where you can choose between a CAB file which you install from the device itself, or using an MSI file through your Windows PC, while your Windows Mobile device is docked.