It does not accept mail. The recipient mail server does not actually accept and deliver email itself. Therefore, emails can be fail or being relayed.
Causes
Indicates a configuration error on the part of the recipient organization.
- For instance, incoming email traffic is being routed through a mail server which has been explicitly configured to NOT ACCEPT the incoming email
Fixes
Step 1: Ensure Not Being Relayed
Check to make sure it is actually failing and not being relayed.
Step 2: Contact The Recipient Mail Server
If the email is actually failing, you may contact the recipient mail sever to determine the reason for not accepting mail.