We have two Active Directory User accounts for one user. To consolodate these back to one account, we remove the email address from the account that we don't want, (in Users & Computers, E-mail tab) and added it to the user that we do want to use. Initially, everything looked fine, except the user had no rights to send. So I made sure he had full rights. It turns out that he cannot send or receive email and we are getting error 1022 Logon Failure on database "First Storage Group\Mailbox Store (servername)" - Windows 2000 account domainname\username; mailbox /o=Exchange/ou=First Administrative Group/cn=Recipients/cn=username.
The use uses a Macintosh with Entourage 2004 and occationally OWA, and also Outlook on terminal services - but mainly Entourage.
Server is 2003 with Exchange 2003, SP2.