Your SOA serial number is: 2315394902. This can be ok if you know what you are doing. This is an alert
Also While there are no direct PTR records, there are reverse ptr records -
Reverse MX A records (PTR)
Your reverse (PTR) record: 184.108.40.206.in-addr.arpa -> mail-mw2nam080138.inbound.protection.outlook.com 10.73.47.104.in-addr.arpa -> mail-dm6nam080010.inbound.protection.outlook.com You have reverse (PTR) records for all your IPs, that is a good thing.
The DNS records for this site, ore actually kinda hinky....
Trust me, I know ALL about DNS. In the 90's I worked directly with Microsoft setting up 2 Servers with ½ a class c license for a Dial up ISP. Windows NT 4.0 was not designed to handle half a class c dns file, and each entry had to be hand edited. I was walking the halls muttering DNS under my breath for a week.
Doesn't that show the PTR for the MX record IP, not the PTR for the A record's IP address. Please, educate me. I used to update and manage DNS records at Cox Business. Part of the training was going over how DNS works so i have a decent understanding but there is always room to grow.