Reverse DNS does not match SMTP Banner

Posted on 2011-05-10
Last Modified: 2012-05-11
I know this question has been asked 100 times, but I cannot get this to work!

We only encountered this problem after we found our mail was not sending to one particular domain ( I did a mxtoolbox test which revealed this "warning - Reverse DNS does not match SMTP Banner". Since then, we have been added to a blacklist and our spam reputation is POOR. We cannot send emails over 32kb to any of our Internode addresses (as Internode uses

I have changed the send connectors FQDN to match our externally hosted MX ( as well as 2 of our 3 receive connectors (the default one will not change).

I have contacted our ISP to add reverse DNS on our main IP  as well as our mail IP.

When doing the smtp diag test, it gives the servers local host name "" when I want it to be ""

Im guessing it is our local DNS that I need to change/add something, but im not to good at DNS stuff...

Any help would be great!!
Question by:Matt Kolkka

    Expert Comment

    Hello GuyRo,

    Are you checked your SPF record? you can also checked from the MXtoolbox. or if you desire, let me know the domain name, in that way I can make a lot of test for you.

    Let me know.

    Thank you,


    Author Comment

    by:Matt Kolkka
    Domain name is ""

    LVL 4

    Accepted Solution

    Your SMTP banner doesn't have to be your FQDN.  It should be according to the RFC but it doesn't have to be and it won't get you blacklisted.  I know lots of people that use the smtp banner as place to put a disclaimer (like anyone is going to read it) or else they leave the default values in there.  You should contact the people you can't send messages to and find out what they are using as a spam filter.  Then go to that website and get yourself delisted.  If they are using a Barracuda spam firewall for instance you would go here:

    By going to the blacklist sites you will also find out why they blacklisted you.

    Assisted Solution

    Hello GuyRo,

    I check it, and was unable to see the SPF record...

    No SPF Record Found. A and MX Records Available
     No SPF record has been found for the domain However, MX and/or A records currently exist for this domain.
     Addresses Listed in A records
    Mail Servers Listed in MX Records
     This information may be of assistance in creating your new SPF record.

    Please contact your hosting support and ask to add a TXT record with this data

    v=spf1 a mx ptr ip4: ~all

    Also request to your ISP to make a PTR pointing to


    Author Comment

    by:Matt Kolkka
    Ok I will leave the SMTP banner alone.  I have contacted the domain I have been having trouble sending to and they have said I was getting blocked due to a lack of reverse DNS, which I got our ISP to correct yesterday (I hope). I sent off test emails and they came back ok. Just have to get off these Blacklists!

    I will see what I can do about adding a SPF record also.

    Thanks :)

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