I have a problem with receiving mails. I do not know if my server or the server of the sender is wrong configured.
I have a domain daniel-marschall.de which has following DNS RR:
daniel-marschall.de. 86400 IN CNAME viathinksoft.com.
The domain viathinksoft.com has the MX RR to "mail.viathinksoft.com":
viathinksoft.com. 85651 IN MX 0 mail.viathinksoft.com.
mail.viathinksoft.com runs Postfix, Cyrus and Debian Linux.
When I send an email to webmaster (at) daniel-marschall.de e.g. using GoogleMail, the user "Daniel Marschall" at our system receives the email, which is correct.
But when the server "startcom.org" sends an email to webmaster (at) daniel-marschall.de , the email gets "hard redirected" to webmaster (at) viathinksoft.com which is a different mail account.
The relevant parts of the email headers are:
Received: from viathinksoft.de ([unix socket]) by viathinksoft.de (Cyrus v2.2.13-Debian-2.2.13-19+squeeze3) with LMTPA; Tue, 06 Nov 2012 02:15:02 +0100 Received: by viathinksoft.de (Postfix, from userid 5001) id AD83016CE112; Tue, 6 Nov 2012 02:15:01 +0100 (CET) Received: from mta1.startcom.org (apache-7.startcom.org [18.104.22.168]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by viathinksoft.de (Postfix) with ESMTPS id 90F5116CE107 for <webmaster (at) viathinksoft.com>; Tue, 6 Nov 2012 02:14:55 +0100 (CET) Received: from localhost (com.internal.startcom.org [192.168.0.180]) by mta1.startcom.org (8.13.8/8.13.8) with ESMTP id qA61EbIS010233 for <webmaster (at) daniel-marschall.de>; Tue, 6 Nov 2012 03:14:37 +0200 From: ... To: webmaster (at) viathinksoft.com (<-- WRONG!!!)
As you can see, the email was initially intended for "webmaster (at) daniel-marschall.de", but now it has the field "To: webmaster (at) viathinksoft.com", so my MTA dropped the mail to the owner of viathinksoft.com .
I think the sender's MTA thinks that "CNAME" RR means that the address needs to be rewritten, but as far as I know, CNAME is only a soft redirect on DNS basis and should not force the MTA to rewrite the domain name. Or am I wrong?
PS: The log entries are showing that my server already has the wrong address when the mail is incoming:
$ cat /var/log/mail.log | grep '90F5116CE107' Nov 6 02:15:00 viathinksoft postfix/smtpd: 90F5116CE107: client=apache-7.startcom.org[22.214.171.124] Nov 6 02:15:00 viathinksoft postfix/cleanup: 90F5116CE107: message-id=<c76cb951ea724270c94ff1b0e8d4de4e (at) startcom.org> Nov 6 02:15:00 viathinksoft postfix/qmgr: 90F5116CE107: from=<certmaster (at) startcom.org>, size=1583, nrcpt=1 (queue active) Nov 6 02:15:01 viathinksoft postfix/pipe: 90F5116CE107: to=<info (at) viathinksoft.de>, orig_to=<webmaster (at) viathinksoft.com>, relay=spamassassin, delay=6.2, delays=5.5/0/0/0.76, dsn=2.0.0, status=sent (delivered via spamassassin service) Nov 6 02:15:01 viathinksoft postfix/qmgr: 90F5116CE107: removed