Reverse DNS

So then,

some mail providers keep sending mail back due to no reverse dns set. I have set a reverse DNS on my rootserver through my datacenter’s online form, but the error keeps coming. I assume, i have to set also a reversedns within webmin/virtualmin. Can i do it once for all domains within a virtualmin installation? Since i have a server running virutalmin and a server running webmin, are there different steps of what to do, so i can reach those hosts, which won’t accept the emails of the various accounts?

Thanks and best.


In order to set reverse DNS, that process is purely set by your provider. There isn’t actually a need to set anything on your own server for that.

If the reverse DNS isn’t working properly, it’s possible your provider hasn’t set it up yet.

What error is it you’re seeing though?


The emails are being returned with the message, Reverse DNS hasn’t been set. It is set through hoster’s webinterface, Don’t i need to add something to the Bind prefs for that? They say it works from their side, but i will keep getting emails back.


There’s nothing you would need to do on your end.

If your provider setup reverse DNS, then you should be all set.

The only other thing is that it’s possible that due to DNS cache or so that some email services may not be seeing it yet.


i would have to do some settings within BInd to respect the reverse DNS being set .

Well then, i will contact the hoster to find out, what is happening there.



Nope, you don’t need to make any changes in bind.

If you like, you can always let us know what the domain name and IP address is, and we can test the reverse DNS for the IP address.

Alternatively, you can run the command “host x.x.x.x” on your Linux server (where x.x.x.x is your IP address), and that will return what the reverse DNS is for that IP address.


I found out, that this is an ISP based problem. The user’s IP adress didn’t have a reverse DNS entry, so Postfix would reject the connection request based on the rules. For doublechecking i have removed the reverse dns check, to find out, whether this was the problem.

Best and thank you.

Yes it is ISP related issue.

In my case, I always called my ISP and request them to set a reverse DNS for the machine/IP/Domain in question. They always obliged and set it up without any charges!

Great, I’m glad you were able to get that working!

i have a vps: =
ip: =
centos v6.6 64bit

I have 5 websites

NOTE : has autoresponder software on it and is the website that will sendout mail (ie autoresponders) … the other 4 websites will also be using this autoresponder to do their email work.
(did a couple of tests including to my google email acnt & google classes anything sent from “” as spam) … Ive not tested any others as yet but Im assuming the others, yahoo, AOL, etc will also state any mail received from “” IS spam.

I checked on for my IP - and every “mx lookup” test on each of the 5 websites reported:

  1. – SMTP Reverse DNS Mismatch – Reverse DNS does not contain the hostname
  2. – SMTP Banner Check – Reverse DNS does not match SMTP Banner
  3. – SMTP TLS Warning – Does not support TLS.

I contacted the VPS owner who said:
We can fix the Reverse DNS but we need what you are wanting it setup as. for example will be reconfigured to … but does not have to be, what ever domain or sub domain you want.

What do i get them to setup up reverse DNS to?

  • ?
  • ? (since this has the autoresponder software & all the other websites will use autoresponder to send replies to whoever requested info)
  • do I get them to setup “reverse DNS” for ALL my 5 websites and/or their respective’s.
    Do i go into “BIND DNS Server” and change each master zones records as not one of the 5 website master zones has a “Reverse Address”.

SMTP Banner Check – Reverse DNS does not match SMTP Banner
SMTP TLS Warning – Does not support TLS.

I also did a DNS lookup and all 5 websites state:

  1. – Local NS list does not match Parent NS list was reported locally, but not by the parent

  2. – Name Servers are on the Same Subnet

  3. – Primary Name Server Not Listed At Parent

  4. – SOA Serial Number Format is Invalid reported Serial 1431925366 : Suggested serial format year was 1431 which is before 1970.

  5. – SOA Expire Value out of recommended range reported Expire 604800 : Expire is recommended to be between 1209600 and 2419200.

For items 4,5 & 6
I compared to Erics reply in post "Bind and name servers”

  • looks like the system hostname isn’t actually the name of any nameservers defined at your registrar.
    =yes = at the registrar =

  • go into System Settings -> Server Templates -> BIND DNS Domain, and set “Master DNS server hostname” to be the name for your primary nameserver
    = yes =

  • existing domains, you’ll need to go into Services -> DNS Domain -> Name Server, and set your nameserver records in there.
    In virtualmin/services/ theres nothing to do with DNS domain/nameserver … but in … server configuration/DNS Records it already shows the nameserver records there for each of the 5 websites already setup.

I think I have fixed items 7 & 8 … to modify SOA records:
Webmin -> Servers -> BIND DNS Server -> Module Config, choose Zone File Options from the dropdown
set “Serial number style” to “Date based (YYYYMMDDnn)”
so Im assuming these 2 items have now been addressed.

I know Ive rambled on a bit but Ive tried to give as clear a picture of my concerns as I can.

Thanks heaps in advance for your helping a newbie!

EM Ind