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Reverse Look up Problem

kdog3445 asked
Last Modified: 2013-11-16
We are having a problem with some ISP's like AOL the do reverse Looks ups on incoming email.

Basicly we have a mail server sitting behind a Watchguard Firewall. The Firewall is doing 1 to 1 NAT from the external IP address to the mail server.

The problem is the External IP adrress the mail is routed from appears to the the Gateway address and not the mail server address.

So if some one send me an email my MX record sends it to
However when I send out and email it comes from my Gateway of

Any ideas?
Watch Question

Pete LongTechnical Architect
Distinguished Expert 2019

Are you using Exchange? if so get your public DNA records set like this

A Record   mailserver.yourdomain.com >  (the outside IP of your firewall)
MX Record for yourdomain pints to mailserver.yourdomain.com
PTR record for mailserver.yourdomain.com that points to

Then on your SMTP server set your masquerade domain to mailserver.yourdomain.com

Then sit back - light your pipe - and admire your handiwork
Pete LongTechnical Architect
Distinguished Expert 2019

oops typo DNA=DNS
Expert of the Year 2007
Expert of the Year 2006

Sounds like your NAT isn't working correctly.

Use http://checkip.dyndns.org/ to see what IP address the traffic appears to be coming from.
You will probably need to review your NAT rules to ensure that they apply to both inbound and outbound traffic.

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Oh yes on last thing. Make sure this filter is higher in the sort order than your filter for your other smtp traffic. Filtering is done in order from rule 1 to rule 250 so if you have any other smtp filters ahead of it in the order it will apply that filter without ever seeing the new filter you just created. Rule of thumb. Always place your specific and deny rules at the top of the list. You can see the order when you open WSM unless you have auto ordering on. Which is a bad thing in my opinion. Do you want the watchguard to control the rules or do you want to control them?

You can change the order mode by simply right clicking on any rule and selecting the order mode.

Hope this all helps.
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