4.5.0 Email Bounce Error
Reason
Unknown Issue With Your Email Server: Delayed Message
The email message has not yet been delivered because the sending email server had an unknown technical problem and could not relay the message properly.
How to fix?
Double check the recipient’s email address to make sure it is correct and attempt to resend the message
4.5.0- Official definition from ITEF
For the code that starts from 4.X.X
A persistent transient failure is one in which the message as sent is valid, but persistence of some temporary condition has caused abandonment or delay of attempts to send the message. If this code accompanies a delivery failure report, sending in the future may be successful.
For the code that starts from X.5.0
Something was wrong with the protocol necessary to deliver the message to the next hop and the problem cannot be well expressed with any of the other provided detail codes.
5.5.0 Email Bounce Error
Reason
Unknown Issue With Your Email Server: Message Not Delivered
The message could not be delivered because the sender’s email server had an unknown technical problem and could not relay the message properly.
How to fix?
Double check the recipient’s email address to make sure it is correct and attempt to resend the message
5.5.0- Official definition from ITEF
For the code that starts from 5.X.X
A permanent failure is one which is not likely to be resolved by resending the message in the current form. Some change to the message or the destination must be made for successful delivery.
For the code that starts from X.5.0
Something was wrong with the protocol necessary to deliver the message to the next hop and the problem cannot be well expressed with any of the other provided detail codes.
