Cannot send to some external recipients after SP3 upgrade of Exchange 2007 #550
Posted on 2013-01-23
After upgrading our Exchange 2007 from SP1 to SP3 we now cannot send e-mail to some external recipients. This issue always appears to involve recipients whose mail domains are being hosted on other domains.
generating server: our.internal.mail.server.net
Most of the NDRs return #550 with various messages including:
some.other.domain #550 relay not permitted
some.other.domain #550 5.7.1 Unable to relay for firstname.lastname@example.org
some.other.domain #553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)
some.other.domain #550 No Such User Here
(this one was a reply to that user)
It would seem to me that the SP upgrade changed something, but I do not know what.
Incoming mail comes through a spam appliance, of which we have a receive connector, plus the typical default and client receive connectors. All of our Exchange roles are on one server, there is one Send connector configured on our server Hub Transport.
Any help would be appreciated.