Federated partner %1 has sent a significant number of messages that have resulted in domain validation failures. There have ...

Federated partner %1 has sent a significant number of messages that have resulted in domain validation failures. There have been %2 such failures in the last %3 minutes.There have been %4 errors in total. This can happen when messages are sent to local users that don't exist, messages are sent from domains that the partner isn't allowed to send from, or when the partner sends messages destined to domains that this organization isn't responsible for.