We ran into an issue today where an older application that we use couldn’t log into our new exchange server when trying to pop mail. (why are we trying to pop when we have Exchange? that’s another story for another day). The Error we kept getting was “ERR Command is not valid in this state”. It’s a pretty simple fix, we just need to enable plain text login for this older application.
- Log into your Exchange 2010 CAS server
- Open the Exchange Management Shell
- Issue command
Set-PopSettings -LoginType PlainTextLogin
- Restart the Exchange POP Service
That’s it. Give the application another go and you should be able to start POPing mail.