Lets say we have 2 domains, domain1.co.za and domain2.co.za. Both point to the same MX records with the same priority, mx1.isp.co.za and mx2.isp.co.za, both of which send the mail through our ISP's filtering/scanning service. From there, mail for both domains is delivered to our on-premises Exchange server using SMTP. In other words, the routing for messages sent to both domains is exactly the same.
- We are seeing consistent failed delivery of messages sent from Gmail to domain1.co.za, but only for some Gmail users. For some Gmail users, messages are consistently delivered to domain1.co.za.
- On the other hand, messages sent to domain2.co.za are delivered consistently, even when sent by Gmail users whose mail is failing to domain2.co.za.
A bounce message for messages sent to domain1.co.za looks like this:
Delivery to the following recipient failed permanently: firstname.lastname@example.org Technical details of permanent failure:=20 Google tried to deliver your message, but it was rejected by the recipient = domain. We recommend contacting the other email provider for further inform= ation about the cause of this error. The error that the other server return= ed was: 571 571 Server listed in SpamCop RBL (state 14). ----- Original message ----- Received: by 10.182.75.65 with SMTP id a1mr18153847obw.32.1326873881149; We= d, 18 Jan 2012 00:04:41 -0800 (PST) MIME-Version: 1.0 Received: by 10.60.8.3 with HTTP; Wed, 18 Jan 2012 00:04:00 -0800 (PST) X-Originating-IP: [220.127.116.11] From: Graeme Donaldson <email@example.com> Date: Wed, 18 Jan 2012 10:04:00 +0200 Message-ID: <CAOBQ9=3Dmx674mUAw1E6_gED11rWzwnFUzWBaKpWLVE_xB8-tGjg@mail.gma= il.com> Subject: test To: firstname.lastname@example.org Content-Type: text/plain; charset=3DISO-8859-1
By contrast, the SMTP headers from a successfully delivered email look like this:
Received: from mx2.isp.co.za (196.x.y.z) by mail.domain1.co.za (172.x.y.z) with Microsoft SMTP Server id 14.1.323.3; Wed, 18 Jan 2012 10:23:23 +0200 Received: from mail-qy0-f175.google.com (Not Verified[18.104.22.168]) by mx2.isp.co.za with MailMarshal (v6,8,4,9558) id <B4f16817a0000>; Wed, 18 Jan 2012 10:23:22 +0200 Received: by qcsp14 with SMTP id p14so2850129qcs.34 for <email@example.com>; Wed, 18 Jan 2012 00:23:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; bh=oC4vJzzjAUASBEWdam7JzvNUOB1qoyAUm0ztpK7fjwA=; b=I/A2jur39kdKCzu57CHzHzeJNbVqcb/e7WV8SDyulEJTKd942OrM+QYkvF8G5Xwkz4 ssZ/p/geoqop0dgTAvoCMcdE1escL3UH3ob3k3Vgs4FqH2aKWYT7LqG3Eb53Z4Kl++K8 D3sD0I8Eb2nZEPLR2pR0K7s8WAtnGb/XgJAws= MIME-Version: 1.0 Received: by 10.229.76.91 with SMTP id b27mr8321239qck.124.1326875001168; Wed, 18 Jan 2012 00:23:21 -0800 (PST) Received: by 10.229.250.66 with HTTP; Wed, 18 Jan 2012 00:23:21 -0800 (PST) Date: Wed, 18 Jan 2012 10:23:21 +0200 Message-ID: <CANFFNku=7OMQZxXd18LtiA7x7V+uj=wiQkKKdA8F_LhwFwiLVw@mail.gmail.com> Subject: test From: User <firstname.lastname@example.org> To: <email@example.com> Content-Type: multipart/alternative; boundary="001d605b95931b230b04b6c92924" Return-Path: firstname.lastname@example.org X-MS-Exchange-Organization-AuthSource: exch.ad.local X-MS-Exchange-Organization-AuthAs: Anonymous
Comparing the SMTP headers, I note that there are 3 "Received:" headers that seem to be entirely within Google's network, with the 4th "Received:" header being the first time it breaks out of Google's network. Looking at the bounce message, it only has 2 "Received:" headers, which makes me think this failure is within Google's network.
Google is notoriously uncontactable for stuff like this so I'm hoping someone else has seen something similar. Has anyone had a similar issue?