Reverse DNS pointer record

First I know the rDNS/PTR record has to be set by the server host. My question is in my environment what name should that DNS setting have.

Server hostname = Bob.ThisDomain.org

Accounts on this Server
ThisDomain.org
ThatDomain.org
MyBestFriendSite.net
TheGuyIreallyDontlike.net

The rDNS/PTR right now is set to mail.thatdomain.org

I seem to be having issues sending email from some thatdomain.org to yahoo/AT&T. I have followed their guides to be more compliant but I question my rDNS setting.

If you want to PM me your actual domain, I could do some outside testing with dig. Otherwise, there are various online DNS testing tools if you want to DIY.

Hostname should have a DNS A record eg: A - bob - your IP

You should also update your RDNS on the server host to bob.thisdomain.org if its currently pointed to mail.thisdomain.org

Thank you both for your help. I opened a ticket to get the rDNS PTR changed and they have already done it. Now i just need to wait for the change to make its way through the dns system.

Cool stuff! 

Be sure to check your mail DNS settings now that your host name is bob.thisdomain.org. There are different ways to set it up but I've listed what I prefer below for you.

mail - A - your IP
webmail - A - your IP
imap - CNAME - thisdomain.org
pop - CNAME - thisdomain.org
pop3 - CNAME - thisdomain.org
smtp - CNAME - thisdomain.org

Lastly ensure you have DMARC, DKIM & SPF set up correctly. These are necessary for many large email providers now. You can check to see everything is good here https://mxtoolbox.com/