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Need help right away, ASA 5505 blocking reverse DNS

Unanswered Question
Aug 26th, 2013
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Just installed an ASA 5505 yesterday. Thought all was well.

When anyone emails into the server they get bounced messages with 550 errors.

   SMTP error from remote mail server after RCPT TO:<radacted>:

    host radacted []: 550-Please turn on SMTP Authentication in your mail client.

   550-redacted (redacted) []:50533 is not

   550 permitted to relay through this server without authentication.

Upon research I'm seeing a reverse dns error in mxtoolbox that that tells me that something is up with my reverse dns.

How do i edit  or ad the nat rule int the firewall to allow reverse dns to see what its looking for?

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Michael Muenz Wed, 08/28/2013 - 02:35
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I'd rather disable esmtp inspection, don't think this has something to do with reverse dns


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Karsten Iwen Wed, 08/28/2013 - 02:53
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The mxtoolbox is probably telling you that the ip-address that you use for Mail is not using the right FQDN. That has nothing to do with the ASA (at least if you send and receive mail with the same IP). You need to contact your ISP to set the reverse-DNS for the IP of you mail server to the FQDN you use for mail.

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