Mail server behind pfSense

  • Hello

    I am using a pfSense firewall in front of an Ability Mail Server. The firewall does NAT for the mail server. when I use MXToolbox to SMTP test the mail server, there are two results:

    SMTP Valid Hostname      Reverse DNS is not a valid Hostname

    SMTP Banner check          Revers DNS does not match SMTP Banner

    I have had a problem in the past where the pfSense firewall IP shows up on block lists, not the mail server IP. I know that since the firewall is in front, that is what any receiving server will 'see' the mail to be coming from. My question is, is there a setting or a rule that needs to be added, so that a reverse DNS lookup will go through to the mail server.

  • The reverse DNS entry has to be set on a public DNS.

  • After you fix your rdns the SMTP Banner is set in the mail server to match it.


  • I checked our DNS, and there are correct PTR records for the domain name. Interestingly, when I use MXToolbox's REverse DNS lookup, the PTR records are there.

  • The MXToolBox result says that the hostname is not valid.
    Hard to give a better support as long we don't know the real hostname.

  • LAYER 8 Global Moderator

    Happy to take a look - but as viragomann correctly states without knowing the domain your taking about its hard to help.. You could PM me the domain and I will check its mx record and the the PTR, and what the banner shows when connecting to the MX, etc.

  • LAYER 8 Global Moderator

    So I got your email.. I replied.  Your PTR returns multiple multiple entries..  1 of which is yours out of the 10 that come back.

    And your banner does not match.. your PTR is mail1.yourdomain.tld while your banner is just some other domain.tld

    So yeah your going to have problems!

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