When a TMG client is installed and providing internet access for the users on a Windows machine, secure email communication through IMAP/POP connection is not possible.
Symantec Corporation is committed to product quality and satisfied customers. This Feature Request is currently being considered by Symantec Corporation to be addressed in a forthcoming version of the product.
Technical Support filed a Feature Request to add this product feature. Note that an feature request is exactly that, a request. There is no committed date for this request from the Endpoint Encryption Product Management team, nor from the Endpoint Encryption Engineering team at this time.
Please be sure to refer back to this document periodically as any changes to the status of the request will be reflected here.
A work around to this issue is to uninstall and reinstall the Microsoft Forefront TMG client.
Alternatively, MAPI can be used instead of POP/IMAP.