Mail server has a generic reverse DNS name
MINORWhat it means
The PTR for the offending value is example.net. the automatic name a hosting provider assigns. It resolves, and it also tells receivers that nobody has configured this machine deliberately, which filters weigh against you.
How to fix it
Set the PTR to a hostname you own, e.g. mail.example.com, and make sure that name resolves back to the same IP.
Check your own domain
This page describes the condition. To find out whether your domain has it, run the PTR test or the full checkup, which examines every record at once.
Understand it properly
This page covers one condition. For the whole picture, Why mail lands in spam, in the order worth checking, or start at the Health Library.
Where this comes from
We judge this against RFC 1912 section 2.1. Every finding on this site cites the specification behind it so you can check the work rather than take our word for it.
Other PTR conditions
PTR_GENERIC
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.