We have a Windows 2003 Server R2, Exchange 6.5.7638.1 and Outlook 2003 & 2007 clients. Exchange accounts work normally in Outlook. Aim is to get POP3 to work so that people could use Outlook for sending/receiving e-mail outside the office too (Outlook Anywhere didn't work).If I create a new user with mailbox in AD and add a that new account in POP3 in Outlook it works. But when trying with all the old accounts it doesn't seem to work. It can't connect to the Exchange server.What might be wrong? There's got to be some difference with the user accounts. I'm trying this internally in the office so I'm not behind a firewall.

Outlook Anywhere does work but its a bit fiddly to set up. We managed to get it working over here after alot of playing. There are some very useful documents online you might want to read about to get Outlook Anywhere and you need a CA on one of your servers todo it then you have to install that certificate on all the client machines like here we had to install the certificate on 6 mobiles as the mobiles are using outlook anywhere via activesync. Have you checked the main pop3 connector? By default pop3 is turned off for all users in Exchange 2007 although you have said you are using Exchange 6.5.7638 which I am guessing is 2007 since you mention Outlook Anywhere which is an Exchange 2007 feature.

It is Exchange 2003, forgot to add. POP3 is on and running...