---
title: Email Bounce Code Analyzer | SendHQ
description: Interpret SMTP and enhanced status codes deterministically while keeping permanent, temporary, and unknown outcomes distinct.
canonical: https://sendhq.cc/tools/bounce-diagnostics
last-updated: 2026-09-24
---
# Email Bounce Code Analyzer

Extract standard three-digit and enhanced status codes from a server diagnostic, then separate temporary and permanent responses without inventing a cause.

## Enhanced status codes

Codes such as 5.1.1 or 4.2.2 have three parts: success class, subject, and detail. The first digit distinguishes success (2), persistent transient failure (4), and permanent failure (5). The remaining digits narrow the category.

## Use the receiver's text carefully

Diagnostic text is supplied by a receiving system and varies. Preserve the original event for support, but do not generalize one response into an address-quality or deliverability claim beyond that attempted delivery.

## Choose retry behavior deliberately

Queue and retry temporary responses with bounded backoff. Permanent responses normally should not be retried unchanged. Suppress recipients only under a documented policy and retain a safe review path for ambiguous provider responses.

## Questions about this tool

**Is every 550 response an invalid address?**

No. 550 is a permanent SMTP response, but the underlying reason can involve addressing, policy, content, authentication, or another condition. Use the enhanced code and server text.

**Should a 4xx response be retried?**

It is a transient class, so bounded retries can be appropriate. Respect provider retry guidance and avoid creating duplicate application jobs.

**Does a bounce prove an address never existed?**

No. It records the receiving system's result for a particular attempt and time.