Email was rejected with the error "no DNS reverse for x.x.x.x"

Every outgoing smtp server should meet certain parameters. One of these parameters is the DNS reverse record of the outgoing IP of the smtp server. It enhances the credibility of the smtp server.

When an email is delivered to the server, it is also checked if the DNS reverse record of outgoing IP is set. Thanks to this check, a lot of spams from common PC with virus are rejected.

If the reverse record is not set, communication with outgoing server is immediately rejected. The sender should get a message with this error:
554 bizsmtp 0bcW1i00G0jifNx01bcmHa no DNS reverse for x.x.x.x
If the sender gets the message with the error above, they should contact the administrator of their smtp server to arrange setting of the reverse record. It is set by the one who assigned the IP (Internet Service Provider, hoster etc.).