Bounce Message

A bounce message is the answer from a receiving mail server when an email cannot be accepted. It contains a status code and usually a text describing the cause, for example unknown mailbox, full mailbox or block by spam filter. Bounces are the most important data source for list hygiene in email marketing.

What types exist

Classically there are hard bounces and soft bounces. Hard bounces indicate permanent problems such as a non existing address. Soft bounces indicate temporary problems such as a full mailbox or a short term server issue. It is worth reading the detailed status codes too, because they distinguish between technical block, reputation problem and content filter.

What you need to do with them

Hard bounces should be removed from the active sending list immediately, because further attempts damage reputation. Soft bounces are retried a limited number of times and then also removed from the active list. Ignoring bounces leads to repeated delivery attempts to dead addresses, which the major mailbox providers notice quickly.

Relevance for JD Mail

JD Mail classifies incoming bounce messages automatically and updates the matching addresses accordingly. You see per send and per list how high the bounce share is and which addresses were taken out. The lists stay clean over time and reputation toward the receiving servers stays stable.