We've got an exchange server, hosted on a Zen connection, and randomly, users get the above error when sending emails. I've inserted 555 in the email addresses to (hopefully) prevent spamming
Generating server: diamond.cor.local
Support@rhombus-systems.com555
smarthost03.mail.zen.net.uk #550 Envelope Sender: Domain must resolve in DNS! ##
Original message headers:
Received: from diamond.cor.local ([10.1.0.4]) by diamond.cor.local
([10.1.0.4]) with mapi; Thu, 17 Jul 2008 09:08:18 +0100
From: NOC Office office@thenoc.org.uk555
To: 'Rhombus Support' Support@rhombus-systems.com555
Date: Thu, 17 Jul 2008 09:08:17 +0100
Subject: FW: RE: done it
Thread-Topic: RE: done it
Thread-Index: Acjnh1ORFScC20oGSIOadCz+7haQ7wAXG6vQAAAKZCoAAAJaAA==
Message-ID: <820CEEA531DF294FA9BF33478B68A700099B04734D@diamond.cor.local>
Accept-Language: en-US, en-GB
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
acceptlanguage: en-US, en-GB
Content-Type: multipart/alternative;
boundary="_000_820CEEA531DF294FA9BF33478B68A700099B04734Ddiamondcorloc_"
MIME-Version: 1.0
This has been happening for a few months, but it seems to be getting worse. Sometimes, resending the email works fine, and it gets through. Other times, a string of these undeliverables appears. I believed I'd tracked the problem to having the sending domain name hosted with 123-reg - so yesterday I transferred it to Zen. Still the same problem.
Any help would be appreciated!