::T-Online ::POLIfórum
IP address: 116.193.90.73
IP address to check

The reverse name of your IP address does not map back to the same IP

EXPLANATION:

We try to resolve the reverse name (PTR) of the sending machine's IP address and then try to resolve that name back to it's IP address.
These two must exist and be the same. You get this error if they weren't, or they did not exist in the DNS, when we tried to resolve them.

SOLUTION:

We could resolve the reverse name of your mail relay's IP address (116.193.90.73), but could not find that name in the DNS.
Please ask your service provider to register an A record for mail.wellborn.co.kr with the 116.193.90.73 IP address.