Class value 4 Retry algorithm

Can you please confirm if for the below Class value 4 , the retry done is at PGi end or to be carried out by our application. Class has three possible values: 2, 4 and 5:
2 – Success 4 – Persistent Transient Failure – applying retry algorithm may be successful 5 – Perman ent Failure – Some change must be made for possibility of success.

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skamens

Our Easylink mail transfer subsystem will generally follow internet standards for retrying based on these codes; therefore, class 4 errors will generally be retried, whill class 5 errors will generally not be retried.

However, class 5 errors usually can not be delivered on a retry (most often they are due to the email address being incorrect or nonexistent), so we do not recommend that you initiate retries for class 5 errors without fixing the root cause first.

It should also be noted that Easylink itself may not be performing the retries for class 4 errors - the indication of a transient failure may be coming from a downstream Mail Transfer Agent (MTA), and therefore those retries may be performed outside of the Easylink system.

Finally, deliveries with class 4 errors can (and often do) fail after retries and lead to a class 5 error later on.