we have a problem in that emails that arrive at our exchange 2003 server (server1) that do not have valid recipients in our organisation are being forwarded back to our isp (who incidentially hold our mx records and route email for us). They are then in turn forwarded back to our exchange server thus created this loop.
I have an internet connector setup on server1 that use the our isp as a smart host. On the smtp virtual server relaying has been disbaled for all except those in our organisation. Also the option of "foward all mail with unresolved recipients to host" doesnt have an entry specified.
Our isp have said they think the problem is at our end but im at a loss to see how?
Does nyone have any suggestions?