4.2.1 Email Bounce Error
Reason
Mailbox Is Not Accepting New Messages: Delayed Message
The email message has not yet been delivered because the recipient’s email inbox is currently not accepting new messages.
How to fix?
Try sending the message again in a few hours or a day later.
4.2.1 – 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.2.1
The mailbox exists, but is not accepting messages. This may be a permanent error if the mailbox will never be re-enabled or a transient error if the mailbox is only temporarily disabled.
5.2.1 Email Bounce Error
Reason
Mailbox Is Not Accepting New Messages: Message Not Delivered
The message could not be delivered because the recipient’s email inbox is currently not accepting new messages.
How to fix?
Try sending the message again in a few hours or a day later.
5.2.1 – 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.2.1
The mailbox exists, but is not accepting messages. This may be a permanent error if the mailbox will never be re-enabled or a transient error if the mailbox is only temporarily disabled.
