This behavior is associated with a feature that was introduced in Windows Mobile 6.1. It provides a way for users to send e-mail through an alternate outbound e-mail server provided by their mobile operator in the event that the default outbound e-mail server becomes inaccessible.
The problem occurs if a mobile operator doesn't use this feature, and therefore doesn't supply a value for the alternate SMTP address. When the mobile device fails on any attempt to connect to the e-mail provider's default SMTP server, Windows Mobile 6.1 automatically loads the value for the alternate SMTP server—which in this case is blank. The e-mail account configuration details are then corrupted, which results in loss of the ability to send e-mail with that particular e-mail account.
With this fix, the feature is patched to ensure that Windows Mobile 6.1 takes appropriate action when it detects a blank value for the Alternate SMTP server.
Note: After you apply this hot fix to your mobile device, the messages that have been sitting in the Outbox folder of your affected POP and IMAP e-mail account(s) will be sent. Since these messages could be out of date, you might not want to send them now. You can keep these messages from being sent by navigating to the Outbox folder of these accounts, and then either delete them, or move them to another folder. On Windows Mobile 6.1 Professional devices, you can access account folders by tapping the folder drop-down located in the upper left portion of the message list. On Windows Mobile 6.1 Standard devices, you can access account folders by pressing the Menu soft key, and then selecting Folders.