---
id: flufl-bounce
version: "5.0.1"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# flufl.bounce — Email bounce detectors

License: permissive · Maintenance: active · Downloads: 681.2K/mo

## What it is and what it does

flufl.bounce is a Python library for parsing bounce messages and extracting the original email addresses that triggered delivery failures. It implements heuristics to handle the many different bounce message formats found in real-world mail systems, and provides explicit support for VERP (Variable Envelope Return Path) and RFC 3464 DSN (Delivery Status Notification) formats.

The library is designed for developers building mail handling systems—particularly mailing list managers and email processing pipelines—where identifying which addresses bounced is essential for list maintenance and delivery monitoring. It requires Python 3.10 or later and depends only on atpublic, making it straightforward to integrate into existing projects.

Use it for:

- Mailing list management: automatically process bounce messages to identify and remove non-deliverable addresses
- Email delivery monitoring: extract bounced addresses from DSN notifications to track delivery failures
- VERP-based bounce tracking: parse variable envelope return path messages to correlate bounces with original recipients
- Bulk email systems: filter and categorize bounce messages to separate permanent failures from temporary issues
- Mail server integration: build bounce handlers that extract addresses for automated list cleaning

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Detects and extracts original bouncing email addresses from bounce messages, supporting multiple formats including VERP and RFC 3464 (DSN).

Yes. The package is mature (Production/Stable, Mature classifiers), actively maintained, has no known vulnerabilities, and solves a specific problem in email handling with low install friction. It is well-suited for any project that needs to reliably parse bounce messages.

## Install

pip install flufl-bounce
uv add flufl-bounce
poetry add flufl-bounce

## Installing flufl.bounce

Before you install: Low install friction with a single pure-Python dependency (atpublic). Active maintenance status with a recent release (84 days ago).

License in practice: Licensed under Apache-2.0 (permissive), allowing commercial and private use with minimal restrictions.

Quickstart:

pip install flufl.bounce

from flufl.bounce import bounce_scanner

addresses = bounce_scanner(bounce_message_text)

Requires Python 3.10 or later.

Verify before relying:

- Specific accuracy or coverage metrics for the bounce detection heuristics across different mail systems
- Performance characteristics when processing large volumes of bounce messages

## Package facts

- License: Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 681.2K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

email bounce detection, bounce message parsing, extract bounced email addresses, VERP bounce handling, DSN bounce processing, email delivery failure analysis, bounce heuristics, email-processing, bounce-handling

[View on SkillFed](https://skillfed.io/packages/flufl-bounce) · [View on PyPI](https://pypi.org/project/flufl-bounce/)