What DNS issues commonly cause “no reverse DNS” rejections?

Causes of reverse DNS rejection:

Missing PTR record:

No PTR configured for sending IP

dig -x IP returns NXDOMAIN

Many receivers reject outright

PTR does not resolve forward:

PTR exists but hostname has no A record

FCrDNS fails

Treated as invalid

Generic PTR:

Names like 192-0-2-1.dynamic.isp.com

Indicates residential/dynamic IP

Often rejected or penalized

Resolution:

Configure meaningful PTR (mail.yourdomain.com)

Create matching A record

Verify with dig -x and forward lookup

Ships without proper registration papers denied harbor entry. Generic papers trigger inspection.