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PTR Record on Exchange server for reverse DNS

Posted on 2011-09-22
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Last Modified: 2012-05-12
Hello,

This doesn't happen often but I got a bounceback today from a comcast mail account that said this:

#< #5.0.0 smtp; 554 imta04.emeryville.ca.mail.comcast.net comcast 208.43.37.159 Comcast requires that all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mail server does not fill that requirement. For more information, refer to: http://help.comcast.net/content/faq/PTR> ##

I need to know where to look up this record and how to find out if my mail server is kosher. Other than this I dont have any issues.

Running SBS 2008 R2 with Exchange 07. File server / mail server.

Thank you for your help in advance.


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Question by:TimberJon
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by:Papertrip
Papertrip earned 250 total points
ID: 36584080
Toss your server into mxtoolbox.com to see all sorts of useful info.  Be sure to check out the different modifiers like mx:, smtp:, ptr:, etc.

If you see something unexpected, paste it here.
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luathas earned 250 total points
ID: 36584112
PTR records are basically the reverse DNS lookup based on the IP address of the mail server. So if you have mail.foo.com = 192.168.1.10 then when someone does a DNS query against 192.168.1.10 the record returned should be "mail.foo.com" and visa versa. Because of unsolicited email on the internet more and more mail administrators are setting this as a rule for potential spammers.

While you may have control over all "forward" looking DNS entries, typically the ISP you get your IPs from will control the reverse lookups. If that is he case you will need to contact them and have them update the PTR record for the IP address that is your mail server.
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Author Comment

by:TimberJon
ID: 36588040
Well I checked it out via mxtoolbox but also took a look at the mx records. There really doesn't seem to be anything out of order except one warning when I looked up smtp:(mydomain).

It says:  Warning - Reverse DNS does not match SMTP Banner

I went into Exchange and edited the settings to fix this but I don't expect the changes to take so soon.

When retesting, it now says that my server hung up on the test before the banner could be pulled. Im really not sure what is causing that...
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Author Closing Comment

by:TimberJon
ID: 36919565
Thank you for assisting with this. Everything seems to be find though I did not have time to really dig into whether or not my tweaking did anything. Thank you both.
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