Microsoft has released a patch for people who had problems accessing SMTP servers.
The hot fix aims to “ensure that Windows Mobile 6.1 takes appropriate action when it detects a blank value for the alternate SMTP server”.
Prior to the release of patch, “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 [a blank value] for the alternate SMTP server. 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”.
Get the hotfix here