By joesciallo on Apr 09, 2007
There was an interesting conversation on the Info-iMS alias last week concerning "bounced email" that caught my eye. Ah, another learning opportunity! To recap, then, here is another installment of Comms 101, courtesy of our Comms experts.
The specific error sited was:
nsmail Illegal host/domain name found (Too many failures to this host during this run; skipping this host: No such host/domain)
The short reply as to what's going on is fairly intuitive: the remote domain in question failed to resolve to a legal result, meaning that almost certainly this is a DNS issue (and not a Messaging Server MTA issue). Note that "other mail" will continue to make it through to your system (expected behavior), so don't be mystified by that activity. In addition, the error message is communicating that the problem has happened multiple times during the current operation (run) of the channel. The message bouncing is thus occurring because of an underlying DNS problem. To troubleshoot this problem, you would need to enable debugging (such as on LOG_CONNECTION) to determine the specific issue. Very likely, such a problem is transitory in nature but it is clearly not an MTA issue. Of final note: fancy configuration workarounds to such a situation are typically more work than troubleshooting and fixing the real problem.
The full detail on this thread can be found here: