I've got an Exchange 2010 server and Outlook 2010. I'm trying to grant a user send-as permissions. I went through EMC to grant that right (and full mailbox access). I can see the send-as permission when I look at the security tab of the "send-ee's" user object. When the user tries to send a new e-mail, she get's a message that says, "You do not have permission to send on behalf of the specified user." However, when she replies to, or forwards a message, she can send the message. I had the user reboot so what gives? Thanks.

Hello, Can you try to have the user select the "From" address from GAL & not use the autosuggest feature of outlook that shows user names from cache. I believe the problem lies around the user using the cache from outlook. so when the outlook suggests a name use a red cross next to the name to remove it from cache & then select both from address from GAL & type the to address manually. let me know if you have a question thanks Sandeep

Turns out the user was entering an incorrect "from address." Thanks.