We host our own email in MS Exchange in MSWindowsSBS 2003. The email is processed locally in MSOutlook 2003. Most of our email works successfully most of the time. But there are some issues which I will describe:
Domain 1 - We were communicating with them successfully through about March 1, 2010. For the last 3 weeks our emails to them (at least 3 individuals) have not reached them. Can we assume that their domain has blacklisted us? But now today at least one of these has gone through again.
Domain 2 - One of our personnel sends email to this recipient several times a day. About 50% of them get through. So obviously this is an intermittent situation.
Domain 3 - This had been working OK, but the last day or so a few emails were not delivered. Today it seems they are going through OK again.
It seems that all emails FROM these domains is reaching us successfully.
I don't know even if these are all the same issue. Of course the intermittency makes it harder to diagnose. If we get blacklisted, I wouldn't have thought that the blacklist flag would just get lifted for no reason. Blacklisting would be something done by a receiving domain, I think. So that would be their issue. But the fact that we have a similar issue by at least 3 receiving domains makes it look like it's something we on our end can fix. It's rather difficult to get enough good data on a situation like this... it interrupts business and our clients have to get involved in IT testing.
Anyway, is there something obvious and straight forward that I can do to troubleshoot this issue?