PTR record is commonly needed for the mail servers. Every mail server has own DNS A record, that points to an ip address, but not all ip addresses have reverse PTR record.
If you do not have PTR records, probably your mail will be rejected from other mail servers. Usually you can't create a PTR record yourself,
because you are not a owner of ip addresses, just domain names. But you can ask your service provider to create PTR records, or delegate this possibility to you.
The best way is to make a reverse DNS PTR record same as DNS host A record for your mail server. Please scroll down this page to see some examples how to check DNS PTR record manually.
You can check PTR record using this page. Your mail servers will be automatically detected. This tool will not check PTR record of individual IP address. To do it, please use this page.