Reverse DNS issue

By trevrow ·
Our mail server runs Exchange 2007. We are getting e-mails held in the queue with 'Possibly Forged Hostname (this being our static IP address of the mailserver.

The static IP address is from Telewest, our 10mb broadband provider. Our mail server is

I have run a reverse DNS test in MXtoolbox and have got 'Reverse DNS does not match SMTP banner.

It appears that the PTR for the static telewest IP is 'host-xx-xxx-xx-x (our static IP address)

Am I right in asking Telewest to change the PTR to ?

Telewest seem to think that it is not their problem.

Any help would be gratefully appreciated.

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All Answers

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insufficent information

by CG IT In reply to Reverse DNS issue

you don't specify how your mail system or DNS servers for your domain name is setup.

Unless your ISP is also your domain name registar and as such, host the authoritative name servers for your domain name, it's not their problem.

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Reverse DNS Question

by MxToolBox In reply to Reverse DNS issue

You are correct that since the reverse IP address name is not contained in the server HELO or EHLO banner it is failing. In the example below, the string ? is not found anywhere in the server banner, which is reporting ?

This is only a warning, and in some cases you may have no control over this. However, if you have the ability to make these match, you should. Some mail servers look for this and use it to mark messages you send as questionable. Most mail systems will not reject your messages outright, but this may effect your spam score increasing the likelihood your messages will be marked as spam.

In other words, it is a best-practice you should endeavor to follow. It doesn?t mean you are a bad person or won?t be able to send email.

220 StrongMail SMTP Service at Wed, 09 Sep 2009 17:00:01 -0700

Not an open relay.
0 seconds - Good on Connection time
0.156 seconds - Good on Transaction time
OK - resolves to
Warning - Reverse DNS does not match SMTP Banner

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it's a simple matter of creating a reverse lookup zone

by CG IT In reply to Reverse DNS Question

on a DNS server for a domain to solve the problem, but we don't know if their mail system actually needs a reverse lookup zone.

If they use hosted POP3 they actually don't need a reverse lookup zone and it's not their problem.

If they use SMTP then it's their problem and whomever created the DNS server goofed by not creating a reverse lookup zone.

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Reverse DNS issue

by trevrow In reply to it's a simple matter of c ...

We do use SMTP however,I didn't set up the server. What should the reverse DNS entry be please ?

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Reverse DNS Issue Resolved

by trevrow In reply to Reverse DNS issue

I finally got my ISP to change the PTR on the static IP address and the problem with 'possibly forged hostname'in Exchange seems to have been resolved.
Many thanks for all your input.

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