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How to setup Reverse DNS on our email server

Hi
I need some help to setup reverse DNS server for our mail server. Before when I used DNS Tools it showed that we had Reverse DNS Server.
Now it says we dont and I dont know why

IP on mail server is: 87.116.17.66
We dont have our own DNS Server on our server

in Imail Software we use, we have to key in DNS Servers and we use our ISP's DNS Servers:
83.136.89.6 and  83.136.89.4

We have 5 domain names + on our server and they are all sending with our smtp server
2 examples are
xxx@e-advice.dk
xxx@dmm-support.dk

When we send mails to some customers we get:
>Server response to MAIL FROM:
>550 5.7.1 Connections not accepted from servers without a valid sender
>domain.nlpi127 Fix reverse DNS for 87.116.17.66

We are using "gratisdns.dk" for all our dns records for all the domains, so I guess I can add something in there somewhere, but I have no idea what

At the moment I have one thing saying:
v=spf1 a mx ip4:87.116.17.66 mx:e-advice.dk ~all  

Can anyone advice me what to do from here?
Any concrete examle on what to write under where in order to get a reverse DNS for our IP that will help all our domains sending from it?


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morten444
Asked:
morten444
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1 Solution
 
Ernie BeekCommented:
SPF records are also good to have, but in this case you need a reverse dns record aka PTR record (but you allready figured that out :)

So, a PTR record is the only record which is not set up by your DNS hosting company but by your ISP.
What you need to do is call your ISP and ask them to set up PTR records for your domains (all five).

Normally your start with a DNS record (human readable) which is translated in to an ip address (computer readable). Because names can be faked, there is also a PTR record. This starts with the ip and get translated in to a (reverse) DNS name. Because the PTR starts with the ip, it has to be set up by the one who holds your ip addresses -> your ISP.
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morten444Author Commented:
Hi. Thanks for your answer:

1 question
If all domains on our server will use the same SMTP Server:
pop3: e-advice.dk
smtp: e-advice.dk

Is it enought that our ISP will create only a record for this one domain name?
We are rapedly getting more sites and would prefere not to contact them every time

Regards
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Ernie BeekCommented:
Mm, that's a good one.

Afaik that will work. But if you are sending emails from other domains from that server you have to make sure that the SPF records are set up to reflect that.

So one PTR should work with the correct SPF records (and those will go through the DNS provider).
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morten444Author Commented:
I see
So our ISP will sort reverse dns

and we will throgh our DNS hosting set a SPF Record for each of the domains sending mails from our server. That means adding a line like this for each domain:
v=spf1 a mx ip4:87.116.17.66 mx:e-advice.dk ~all
v=spf1 a mx ip4:87.116.17.66 mx:dmm-support.dk ~all

etc
Have I understood that correct?
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Ernie BeekCommented:
You're understanding it quite good.

The PTR record is to check if your mailserver is who it says it is.
The SPF records are to determine what servers are allowed to send mail for your domain(s).

That's all there is to it ;)
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morten444Author Commented:
Thanks
We have now resolved the reverse DNS with our ISP.
Thanks for all your help
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Ernie BeekCommented:
Glad I could help :)

And thx for the points.
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