Setting up Reverse DNS for Smartermail?
Question asked by Francis Gibbons - 5/22/2017 at 1:44 PM
Hello All,
I'm running Smartermail 15.5 on a Windows 2012 system. I have multiple domains running email off my server using IP x.x.x.19. However, my one domain njpsac.org gets a rDNS rejected email from time to time saying:
Reason: Failed to connect to the recipients mail server.  No DNS information
was found for the 'njspac.org' domain.
Status: 544 5.4.4 Host not found (not in DNS).
But if you do a rDNS lookup it comes back to mail.gdishosting.com which is my hosting company and not mail.njpsac.org which is my customer. However my IP hosting company only allows me to setup rDNS for 1 domain so I can't add mail.njspac.org along with all other domains sending mail out of x.x.x.19. So with that said how should I setup smartermail to handle reverse DNS for this IP so all mail will be valid with rdns?
Frank G.

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echoDreamz Replied
Over the years with SM, we have had some strange results with rDNS lookups. IE failures when there was no reason to fail, passes when there should not have been.

My biggest issue is it seems that SmarterMail does not also perform forward confirmations.
Stephen Smith Replied
I have this same question!!
Stephen Smith Replied
OK, for those that might stumble on this thread in the future.   Here is how I solved this issue, and attained a perfect SpamAssassin score with our multidomain mail system.

1) Yes, PTR must be set up by hosting provider, and the IP you should be using is the publicly exposed mailserver IP (can be obtained by taking your RAW email header and put it into any email header analysis website). This will show the IP and main host header you are expressing in your SMTP banner via SmarterMail. There is only one expressed, even if you have 50 domains.

2)  The second important, and key point, is that you must setup DNS record for that host header record (mine is securemail.stevemail.com)   and the IP address used in the dns record of securemail.stevemail.com  MUST be the same as what is being expressed in your SMTP banner.

Those to reverse DNS and forward DNS settings must match, and then you are golden. I saw someone illustrate the records like this:
host header domain >>>> 344.24.12.761 must match
344.24.12.761 >>>> host header domain

A good email testing system is http://www.mail-tester.com

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