What we have is Exchange 2013 using Websense server as a smarthost to send/recieve email.
We have some users who are set up with server-side forwards to external email addresses.
What happens at the moment:-
1) Email from internal user A to internal
user B (who has forward setup). Email gets forwarded to user B's
external email.
2) Email from external user C to internal
user B (who has forward setup). Email gets bounced with 551 error abck
to external user C.
I assume its because something (Exhchange
or Websense) is detecting that the original sender is not the same
domain as the exchange server that is attempting to forward. Which sort
of makes sense.
BUT, we've recently moved from 2007 where
this used to work. So theres something - on old Exchange 2007 or
Websense that has allowed this previously.
Appreciate its not a wise move to allow this sort of thing but it is what it is.
By the way, its NOT remote domain setting
on Exchange. This applies ONLY to client side forwarding.
Here is the error:-
userB@hotmail.co.uk (user Bs external email)
websense.xyz.gov.uk (Websense server)
Remote Server returned '551 This is not a relay host - mail must be to or from host domain.'