A Delay DSN (Delivery Status Notification) is a type of bounce message that indicates a delay in the delivery of an email. Unlike hard bounces that signify permanent delivery failures or soft bounces that point to temporary issues, delay DSNs inform the sender that the message has not yet been delivered but is still in the process of delivery.
When an email server receives a message but cannot deliver it to the recipient immediately, it generates a delay DSN. This notification is sent back to the sender to inform them of the delay. The email server will continue to attempt delivery for a specified period (usually 48-72 hours) before giving up and generating a permanent failure notification if the message still cannot be delivered.
Common Reasons for Delay DSNs
Several factors can contribute to the generation of a delay DSN: