What are the recommended bounce classification codes (per RFC 3463)?
RFC 3463 defines enhanced mail system status codes that provide detailed information about delivery results. These three digit codes (like 2.1.5 or 5.1.1) supplement basic SMTP codes with specific failure reasons.
The first digit indicates class: 2.x.x for success, 4.x.x for temporary failure, 5.x.x for permanent failure. The second digit indicates subject: x.1.x for addressing, x.2.x for mailbox, x.7.x for security. The third digit provides specific detail.
Common codes include 5.1.1 (bad destination address), 5.2.2 (mailbox full), 4.2.2 (mailbox full, temporary), and 5.7.1 (message rejected for policy reasons). Proper bounce classification using these codes enables appropriate handling.
Was this answer helpful?
Thanks for your feedback!