We have an Exchange hybrid setup between O365 and a linux server installed on a VPS. O365 is the front server and all inbound and outbound emails are relayed through it.
Before connecting the two servers, we setup successfully the reverse DNS on the VPS. Now that we have connected the two servers, we don't know how to setup the reverse DNS for O365. We don't pass Mail-tester anymore and get the following error message:
"Your IP address 40.107.xxx.xxx is associated with the domain mail-viXXXXXXXXXXX.outbound.protection.outlook.com.
Nevertheless your message appears to be sent from EUR05-XXXXXX.outbound.protection.outlook.com."
Our DNS are managed by Squarespace and we have added an TXT spf record: "v=spf1 ip4:xxx.xxx.xxx.xxx include:spf.protection.outlook.com -all" with "xxx.xxx.xxx.xxx" the IP of the VPS.
We read a number of answers on this forum, but without founding a solution.
It would be great if someone could help.