Record ptr reverse dns

[omar]

when i instal hestia i have done the hostname like in this message of the forum

Reverse DNS Practice for Mail Server

In setting up a mail server, what should we setup as a reverse DNS? mail.mydomain.com or mydomain.com The reason I’m asking is that I’ve checked with both mail-tester and mxtoolbox. They seem to have a different idea on what should be in the reverse DNS ptr. In my case, both domain and sub-domain are in the same server sharing the same email address. Thanks for any feedback.

cheers
Omar