PTR Record

It should really match the A record that your MX record uses.

for example your MX record should point to an A record like mail.domainname.com

You then need to ask your ISP (BT Openworld) to setup an rDNS(PTR) record for your IP address of mail.domainname.com

I have an article here that should help: https://www.experts-exchange.com/articles/Software/Server_Software/Email_Servers/Exchange/Exchange-DNS-Configuration.html

>>I've tried contacting BT support but they didnt even know what a PTR record is.
This is not unusual.  I have lots of problems with BT

if u have windows dns check..
when you add A host record. you must check the box for add PTR Record..

-From DNS Manager, open your forward zone.
-Right-click on the "A" record for your DNS server, and then click Delete Record.
-Click Yes to confirm the deletion of the "A" record.
-Right-click on the forward zone, and then click New Host.
-Type the host name of your DNS server and the IP address.
-Select the Create Associated PTR Record check box.
-Click Add Host, and then click Done.


if unix check

this is for the zone..write inside named.conf

zone “1.168.192.in-addr.arpa” {
   type master;
   notify no;
   allow-query { any; };
   file “192-168-1.zone”;
};

The comment above is not relevant for sending e-mails out of your organisation.
This is talking about INTERNAL DNS not EXTERNAL DNS

Sweet.  Thanks for the comments guys.

So I need to change the A record of the domain to point back to the IP of where the mail is originating? ie our public mail server IP that we have in our building?

Is it simpler to change our mail server announce to what the PTR currently is for the IP?

No, all you need to do add a Reverse DNS record for the same name as your A record that the MX record uses.
Please follow my guide.

are you saying to put mail.mydomain.com as the ""A"" record  or nameserver racord?  so we dont put the IP in the A record then?

OK, you haven't read my article yet?

this is how it should look:

A Record = mail.domainname.com IP of 111.222.111.222
MX = mail.domainname.com
rDNS = mail.domainname.com

I did read - just want to be sure :-P

we use an external POP 3 mailserver different to the one we use to send

Please ammend above

Also if I go to change the A record then it only allows me to put an IP in not a name

The A record WILL only allow you to specify an IP address.
You don't need to change this.
You need to add an rDNS record that is the same name as your A record that the MX record uses.

The MX needs to remain pointing at the external server IP otherwise we wont get mail.
I have asked BT to add the PTR for our public facing IP to be mail.ourdomain.com

You need to add an rDNS record that is the same name as your A record that the MX record uses.
How does an MX record use an A record?

An MX record MUST use an A record.  This is all explained in my article.
An MX record should not be pointing to an IP address the A record should point to the IP address and the MX record to the A record.

So..

A Record is set to our public IP
MX has to stay as IP of 3rd party hosted pop server
PTR of OUR Ip is set to mail.domain.com

Am I missing anything?

Your MX record should point to an A record.
If you have to configure that A record to the IP of your 3rd party hosted service then that's fine.
Your PTR record should then be the same as the A record.

I thought the MX record is whas is used by people wanting to send us mail, so if we change the MX record to something other the actual mail server that we get email from then how is incoming mail going to work?