I am trying to setup an external SMTP relay for a customer that has SBS 2011, so that their CRM application they are looking to use can use it's own email client, which only supports IMAP.
IMAP is up and running ok, and I have setup a receive connector using port 587 with TLS and basic authentication for Exchange users.
I have setup a test user, and added it to a group that I created, and given that group SMTP rights via the following command
Get-ReceiveConnector "default frontend*" | Add-ADPermission -User "contoso\relay accounts" -ExtendedRights ms-Exch-SMTP-Submit
I have even added the user in as individual rather than a group using
Add-AdPermission -Identity “Default SERVERNAME” -User Username -ExtendedRights MS-Exch-SMTP-Submit
When I go to use Outlook as a test, I just keep on getting 550 5.7.1 Client does not have permissions to send as this sender.
I have checked the rights in the users mailbox and they are set to self, I have even tried adding the user to the send as permissions to it's own mailbox, and not matter what I do, still get the above error.
I have been been over everything in the following website (http://blog.korteksolutions.com/how-to-enable-relaying-for-external-clients-on-sbs-20082011-and-or-exchange-20072010-with-different-sending-email-addresss/
) but still just keep on getting the error message.