I have a client with 2 domains in their Exchange Server. One particular user needs an account from each domain set up in his profile in Outlook 2010. This was working for some time, then about a week ago it suddenly stopped.
When he sends an email or replies to an email from the primary domain, no problems are encountered. However, now when he sends an email from the secondary account it will sit in the "Outbox" and not go anywhere. Also, if he receives an email to the secondary account, and replies to it, a bounce back will appear in the "inbox" in the primary account which states that "The user does not have permission to send from this account."
If I log into the Exchange Server I am able to correct the problem by granting the primary account "send as" permissions to the secondary account. However, the permissions go missing after about a day or two, and I'm stuck at square one.