Расшифровка частых bounce-ответов

Ошибки недоставки

550 Spam Message Rejected

550 5.7.1 Blocked by SpamAssassin

Ошибка 550 From address violates UsernameCaseMapped policy

Ошибка 550 5.7.0 Message rejected under suspicion of unsolicited email

Ошибка 550 Message was not accepted -- invalid mailbox