I have a mail-enabled public folder that I am trying to allow users to send on behalf of from Outlook, but have thus far been able to figure out the appropriate permissions to grant. If the mail-enabled public folder named "folder@domain.com" has an email address of "folder@domain.com" and I am trying to grant the user "user" to send as the folder, shouldn't the following commands get me there? (1) Set-MailPublicFolder "\folder@domain.com" -GrantSendOnBehalfTo "user" (2) Add-ADPermission "folder@domain.com" -User "user" -ExtendRights "Send As" After running those two commands and attempting to create a new email message in Outlook (logged in as "user") that is being sent as "folder@domain.com" I get an Undeliverable back with the following message: You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission. Does anyone have any suggestions to help me resolve this issue?

You should either grant SEND AS or SEND ON BEHALF permissons for that folder to the user, not both.

Thank you for your response. I don't know what I was thinking when I was doing that - but you are (clearly) correct. In this instance the issue seemed to actually be the sytanx of my command - "-ExtendRights" vs "-ExtendedRights". I am not sure why I didn't notice that it had thrown an error - that seems very odd to me. Thanks again for your assistance - it was much appreciated.