Hi,
A friend with a hotmail email address has not been able to send to my email address hosted on Axigen 10.3.3.53 - he receives a 550 5.7.364 error relating to rDNS failures. I tried from an outlook.com address and get the same. Gmail senders are received fine.
I assume the rDNS lookup is the Axigen server looking for Outlook – free personal email and calendar from Microsoft to check it matches with the IP address of the email server it’s receiving the email from - in which case I have no control over the records. Is there something in the filters that allows these domains to be received from?