A customer e-mailed today about an Outlook Security Alert that was showing up on one of their workstations. I used Remote Desktop to log in to the PC to check on the error.

Since this was one of my customers using my hosted Exchange service I first checked the certificate to make sure it was from our Exchange provider. It looked fine, so I clicked the 'Yes' option and all worked well. The problem was that the alert box still came back each time they open Outlook. After a few minutes away from the issue, I realized that the problem must be in the Outlook settings because we're not using encryption and shouldn't need a certificate at all. I reconnected with the PC and went to the 'Security' tab in the account settings, unchecked the 'Encrypt data....' box and the warning went away and stayed away.

I know there are lots of different causes and solutions to this but most are related to the Exchange Server setup. Since this is a hosted service, the best solution was a quick fix on the client side.