Exchange Server 5.5 installed on NT4.0.
The outbound messages have been slowing down (incoming OK). I checked the IMS outward messages queue and it is filled with 10s of thousands of obviously spam messages. As soon as you delete one batch of 10,000 (the maximum shown in the box) another 10,000 pop up. I think this has only happened recently - although I cannot discount the possibility that these have been building up for a long time as our maintenance has not been as good as it could be - I am from a very poor developing country.
I think this might be due to relaying, which brings in the second point. On our internal network (which uses NAT and fixed IPs) we have one host which needs to relay, because of some HF radio email software which it runs (i.e. that host is a gateway for a radio email network). If I disallow all hosts from relaying, the radio email does not work (outward messages get the relaying probibited error). In the Exchange server IMS properties , routing, routing restrictions box I am only allowing (1) hosts that authenticate AND (2) the host with the internal IP address for the radio email computer. I am not 100% sure that relaying is completely prohibited.
Can I have your kind advice on what angle of attack I should take? How can I configure the routing restrictions so that that single computer with the radio email is allowed to relay without getting general relaying occuring? Should I enter the IP of the SMTP server where Ex Server is installed in the NEVER relay box (sorry if that is a stupid question)?