4.3.0 Email Bounce Error
Reason
Unknown Issue With The Receiving System: Delayed Message
The email message has not yet been delivered because of an unknown problem with one or more of the recipients’ email systems.
How to fix?
Double check that the recipient’s email address is correct. Wait a few minutes, then try sending the message again or try contacting the recipient in other way.
4.3.0 – 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.3.0
The destination system exists and normally accepts mail, but something about the system has caused the generation of this DSN.
5.3.0 Email Bounce Error
Reason
Unknown Issue With The Receiving System: Message Not Delivered
The message could not be delivered because of an unknown problem with one or more of the recipients’ email systems.
How to fix?
Double check that the recipient’s email address is correct. Wait a few minutes, then try sending the message again or try contacting the recipient in other way.
5.3.0 – 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.3.0
The destination system exists and normally accepts mail, but something about the system has caused the generation of this DSN.
