Hi all,

at a customer's site we are running a GW 8 server on OES2 Linux.

It was all fine, but for a few days the customer keeps getting 550 errors on delivering mails to some domains, not all.

I've read the forum and checked the DNS resolution using nslookup for the unreachable domains. nslookup ran fine an reported the correct MXs. I then replaced the DNS servers in the machines config with some others, GWIA was still getting the same errors. I even changed the packet size on the router, same errors. I tried to telnet to the unreachable machines on port 25, which ran fine too.

So the GWIA seems to be the only one who's not able to reach these machines, the rest of the servers services are able to.

Any help would be greatly appreciated!