What is a Delayed Bounced of an E-Mail

Delayed bounces are not common in the email world, however, you may encounter them from time-to-time.

Since the recipient server returned 250 OK in the SMTP transmission, they accepted the hand-off of the message from Qfast; this “250” response will generate a “delivered” event on your end.

Once the message is delivered, the email contents may go through multiple email processes including spam and other email policy checks which generates “opened” and “clicked” events. It may finally go through an internal placement processing, during which it would have determined, that the recipient address did not exist and issued an NDR (nondelivery report). When Qfast receives the NDR, we then generate a “failed” even for the message in the logs. It was only after the message handoff that they determined to reject the message for a given reason and then notify of the rejection by responding to the Return-Path address.

This process will generate an “accepted” event, “delivered” event, and then ultimately a “failed” event once the NDR is processed.