Interpret the bounce reason
Temporary failures can result from a full mailbox, rate limiting, or a brief receiving-server outage. Review the response code and provider guidance because a temporary condition may clear without any change to the address.
Permanent failures often indicate an invalid or nonexistent recipient, but the exact response matters. A policy rejection or blocked sender can look permanent while requiring a configuration or reputation fix rather than deleting a valid contact.
Choose a measured response
Use bounded retries with delays for temporary failures and stop after the documented retry window. For permanent failures, suppress the address from repeated marketing sends until the address or rejection cause is verified.
Review bounce trends by provider and campaign, not only a single event. If many valid recipients suddenly bounce, investigate authentication, sending volume, and message policy before removing contacts in bulk.