We have several IP addresses assigned to this computer. While the machine itself is 111.222.333.1, we have assigned 111.222.333.2 to GMS Mail. But the GMS Mail Post service communicates as 111.222.333.1, not 111.222.333.2.
We had our ISP set up reverse DNS for 111.222.333.2, but not for 111.222.333.1. Now we are having emails rejected by mail servers that do a reverse DNS lookup.
GMS Mail uses the primary IP address on a network card to post all outgoing mail. Set a reverse lookup for this IP address to point to the domain that mail is coming from.
Using the above as an example, and assuming that the GMS Mail is running on a machine called host and servicing mail for the domain domain.com. Ensure that a reverse lookup on the IP address 111.222.333.1 maps to host.domain.com
Keywords:Reverse Lookups, Post, outgoing, queue