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Email Deliverability · Bounce handling

Email bounce handling and CAN-SPAM compliance in the United States

Short answer

CAN-SPAM requires accurate headers, a physical address, and honoring opt-outs within 10 business days. Email bounce handling supports compliance by making sender identity verifiable and recipient choices enforceable.

What CAN-SPAM requires#

CAN-SPAM requires accurate headers, a physical address, and honoring opt-outs within 10 business days.

What email bounce handling is#

Bounce handling is the automated processing of delivery failure notices (DSNs) to classify hard versus soft bounces and suppress addresses accordingly.

Why it matters#

Repeatedly sending to invalid addresses is one of the strongest negative reputation signals providers track.

How email bounce handling supports CAN-SPAM compliance#

Regulators and recipients need to identify who sent a message and trust that opt-out mechanisms work. Email bounce handling contributes by repeatedly sending to invalid addresses is one of the strongest negative reputation signals providers track.

Implementation steps#

  1. Parse DSN codes: 5.1.x means the address does not exist (hard); 4.x.x means temporary (soft).
  2. Suppress hard bounces after one failure and soft bounces after three.
  3. Route bounce notifications to a monitored mailbox or webhook.
  4. Review bounce reasons weekly for patterns like 'blocked' that indicate reputation issues.

Frequently asked questions#

What is the difference between a hard and soft bounce?

Hard bounces are permanent failures (bad address). Soft bounces are temporary (full mailbox, server down). Suppress hard immediately.

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