I have added a 2nd authoritative domain in Exchange 2010. Added the alias's to the users I want to receive mail from the new Domain. I am unable to see the drop down in Outlook so the user can pick what email address to send from. When I try and manually type in the address it gives error about not being authorized to send emails from that account. Its the same Active Directory account that has the alias. What changes do I need to make to see the drop down addresses in the FROM field in Outlook. And to allow permission to send from the same Active Directory account. I don't think its anything major but can't find what I am missing on this.