I have a weird situation here. Currently, we are migrating from MDaemon to Exchange 2013.
As it's setup now, MDaemon is acting as a smart host for the Exchange server. This allows us to move individual users from MDaemon to Exchange as time permits. Exchange sends all mail to the MDaemon server, which then passes it to a Barracuda Spam & Virus firewall.
I've started moving some devices that send email to inside and outside users (IE: IBM iSeries 5, Sharp copiers, etc). I created a Hub Transport for these units and authorized their IP address to pass mail to the Exchange server.
These units can send to internal users on both MDaemon and Exchange without a problem. However, when they try to send, using the SMTP gateway on Exchange, to outside users they receive an error. 550.5.7.1 Unable to Relay.
Exchange users can send/receive to the outside world, through MDaemon, without any issues. They can receive email from the outside world just fine.
Is there something I could be missing?
EX of errors received back from IBM server when trying to send to a gmail address:
NOT ABLE TO DELIVER MAIL TO SOME/ALL RECIPIENTS.
REPLY CODES WITH FIRST DIGIT = '4' OR '5' ARE ERROR REPLIES.
ERRORS THAT DO NOT HAVE ERROR REPLY CODES MAY EXIST.
HOST S1015FE4 NOT ABLE TO DELIVER MAIL TO FOLLOWING RECIPIENT(S):
MAIL REJECTED BY gmail WITH THE MESSAGE:
550 5.7.1 Unable to relay