The diagnostic code in a bounce normally explains whether the problem is temporary, permanent, policy-related or address-related.
Applies to: Failed outgoing email
Read the useful parts
| Part | What it tells you |
|---|---|
| Status code | 4.x.x normally indicates a temporary failure; 5.x.x normally indicates a permanent rejection. |
| Remote response | The recipient server’s reason, such as unknown user, policy, reputation, authentication or message size. |
| Recipient | Which address failed; other recipients may have succeeded. |
| Timestamp and server | Where and when the rejection occurred. |
| Original message ID | Helps Support trace the attempted delivery. |
What to do
- Confirm the recipient address is exact.
- Do not repeatedly resend an unchanged message after a permanent
5.x.xrejection. - For a temporary
4.x.xresponse, allow normal retrying unless the message is urgent. - For SPF, DKIM, DMARC or reputation responses, use the related authentication/reputation guidance.
- Keep the complete bounce when contacting Support; screenshots often omit the diagnostic detail.
Related articles
- Troubleshoot hosting email sending and delivery
- Investigate email rejection caused by IP or domain reputation
- Set up SPF, DKIM and DMARC records
- Roll out DMARC safely from monitoring to enforcement
Last reviewed: 2026-07-25.
