Bounce handling
Receiving, parsing and acting on bounces automatically: classifying each failure and suppressing, retrying or flagging the address accordingly.
What it means
Bounce handling has two inputs: SMTP replies in the sender's own logs for failures during the session, and bounce messages arriving at the envelope sender address for later ones. Each failure is tied to a recipient, through the DSN's Final-Recipient field, an ENVID or a VERP address, classified as hard, soft or block from its reply and enhanced status codes, and then acted on.
Typical rules: suppress after a hard bounce; suppress after several soft bounces in a row; do not suppress for a block, which concerns the sender; treat auto-replies and challenge messages as something other than bounces. Postmark exposes such bounce types through its API, Amazon SES requires senders to have a system in place for managing bounces and offers notifications for them, and Google asks senders to unsubscribe recipients who have multiple bounced messages.
Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- RFC 3464: An Extensible Message Format for Delivery Status Notificationsrfc-editor.org
- Postmark API: Bounce typespostmarkapp.com
- Amazon SES Developer Guide: Monitoring sending activity using notificationsdocs.aws.amazon.com
- Google, Gmail Help: Email sender guidelinessupport.google.com
All 432 terms in the glossaryThe wiki: blocklists and bounce codes