Emails can not be sent or received by the mail server due to blacklisted IP address of the mail domain

Symptoms

Emails can not be sent or received by the mail server in ispmanager 6.

Root cause

The IP address of the mail domain is blacklisted.

Resolution

Outbound mails may not be delivered because the IP address of the mail server is blacklisted. You can check if an IP address is on any blacklists using third-party services such as MXToolbox or DNSBL.

If the IP address is present on at least one blacklist, contact the blacklist holder (the name will be indicated in the verification service output) to exclude the address from the list. If you rent a VPS from a hosting provider, contact the hosting provider support service for assistance.