SOLVED Possible rDNS issue

monkey64

Well-Known Member
Nov 6, 2011
123
5
68
cPanel Access Level
Root Administrator
I'm experiencing issues sending emails to, in particular, gmx addresses. The error received indicates a bad PTR record:

Code:
Action: failed
Final-Recipient: rfc822;[email protected]
Status: 5.0.0
Remote-MTA: dns; mx00.emig.gmx.net
Diagnostic-Code: smtp; 554-gmx.net (mxgmx015) Nemesis ESMTP Service not available
554-No SMTP service
554-Bad DNS PTR resource record.
554 For explanation visit https://www.gmx.net/mail/senderguidelines?ip=12.34.56.91&c=rdns
I checked out the URL in the error and everything looked fine until I ran a HELO test and the error received was:

Code:
550 *** The HELO for IP address 12.34.56.91 was 'server-91.myserver.com' (valid syntax) ***
Reporting-MTA: dns; server-215.myserver.com
The domain I'm sending from has a dedicated IP 12.34.56.215 and the main server address is 12.34.56.91. The domain has valid DKIM, SPF records etc and we experience no other sending issues. If I look at the 'Email Deliverability' section in the user's cPanel, there is a blue warning which says:

Code:
The system uses an alternate HELO of “server-91.myserver.com” when sending mail from the “mydomain.co.uk” domain.
I did try setting the 'Send mail from the account’s IP address' in the Exim Configuration Manager to 'Off' and rebuilding the RDNS cache but I still received bounces. I'm not sure what I need to do to fix this other than removing the dedicated IP entirely and sending everything from the server IP.

Can anyone help me please?

Thanks
 

monkey64

Well-Known Member
Nov 6, 2011
123
5
68
cPanel Access Level
Root Administrator
Although dig showed that the rDNS pointed to the correct domain name, I don't think the change had fully propogated. Shortly after writing this post everything started working. Typical :)

Code:
dig -x 12.34.56.78 +short