We have moved all our users from an old Exchange 2003 to a new Exchange 2010 SP1 server. There was no problem regarding the moving process. All users can log in with OWA on the new server. But there are still some users who want to use Outlook Express. And some of these users experience the same problem: They cannot download new emails.
This problem does not occure for all the users, some have 2 different computers with 2 different account, and it work on one computer but not the other. The error message they receive is:
There was a problem login onto your mail server. You User Name was rejected. Account '%name%', Server '%serverIP%', Protocol: POP3, Server Response: '-ERR Command is not valid in this state', Port 110, Secure(SSL): No, Server Error: 0x800CCC90, Error Number: 0x800CCC91
I have notices that this occurs on different OS, on some machines there are anti virus, and some do not have anti virus. Some run OE and some run Outlook 2010. So I cannot see a pattern on the computers that dont get the connection. And keep in mind that these users can still logon the OWA, so I know we are using the right username/password.
So does anyone have any good tip to possible solution to this problem?