My Nokia E71’s Nokia Mail for Exchange (2.9) suddenly kept insisted on a secure connection. This is even when I have set it in the profile.
Recreating the profile gave the same result. I re-installed the Mail for Exchange application with no success. Frustrated, I reset the phone, it still kept asking for secure connection. It seems that the flag is stuck somewhere in the Symbian OS. Looks like more drastic measures are required.
In the end, I removed the application, deleted the server certificate, restarted the phone and installed the application . That did the trick.
The certificate management screen can be found in Tools, Settings, General.