We have seen a couple of domains out there that we cannot email to since we made the move from our old server to our new one.

We had this problem once before a few years ago , and I am pretty sure it ended up being a PTR issue, where the recipient Domain did a reverse lookup and got a mismatch. But I also remember somewhere that we had to update some kind of record pointing to our SERVER host name and not just to our internet subdomain.

So we called the ISP and set up a PTR record to match our A record for the subdomain. Mail.<domain>.com

And an A record for Mail.<domain>.com ( which was already there )

Now , We didn't have a PTR setup up at all for the past year and Emails were flowing to this company fine until we changed servers ( both behind the same public address )

Now I've been informed that we probably need to setup a second PTR record to point to the HOST name i.e. Host.<domain>.com.

But reading this link :
Setting up PTR's (aka Reverse DNS)

It says that only ONE PTR record per IP. So we wouldn't be able to create two ( 1-Mail.xxx.com and 1-Host.xxx.com )

So , Where does the Hostname of the new Server fit in here ? Do we need to create an A record ? Or is there somewhere in Gwia that we need to tell it NOT to use the host name on outbound SMTP and to use the subdomain name for reverse lookups ?

Thanks in Advance.