# MailFail

> MailFail identifies and provides commands to exploit a large number of email-related misconfigurations for the current domain and subdomain. The extension's UI popup highlights any misconfigurations in red and links to supporting documentation.

Canonical page: [https://chrome-stats.com/d/mailfail](https://chrome-stats.com/d/mailfail)

## Overview

- **ID:** `mailfail`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Hacks and Hops
- **Category:** web-development,privacy-security
- **Daily users:** 103
- **Weekly downloads:** 1
- **Rating:** 5.00 / 5 (2 ratings)
- **Version:** 1.0.21
- **Last updated:** 2025-03-04
- **First published:** 2024-02-28
- **Size:** 528 KB
- **Data as of:** 2026-09-08
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/mailfail/)
- **Website:** [https://github.com/ACK-J/MailFail](https://github.com/ACK-J/MailFail)

## Description

MailFail is a powerful, free, and open-source Chrome extension designed to identify and exploit a wide range of email-related misconfigurations for domains and subdomains. It covers protocols such as SPF, DMARC, DKIM, ARC, BIMI, MX, MTA-STS, DANE, DNSSEC, SMTP TLS Reporting, ADSP, and more. The extension's user-friendly popup highlights any misconfigurations in red and provides direct links to comprehensive supporting documentation.

Developed out of a desire to simplify the complex nuances of email security protocols, MailFail consolidates various edge cases into a single tool, saving users from sifting through dense RFCs. It operates using CloudFlare's DNS over HTTPS for private and reliable DNS queries and has minimal permissions, including notification display for severe issues and browser tab access for context-aware operation. The fully auditable source code is available on GitHub, and users can test functionality directly via the https://m.ail.fail/ website.

## Rankings

- #11,451 — Overall
- #73 — hotmail
- #74 — mail
- #90 — identify
- #134 — email
- #150 — gmail

## Permissions and access

### Permissions

- `notifications`
- `tabs`
- `storage`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Low risk likelihood

### Analysis details

- Grants access to browser tabs, which can be used to track user browsing habits and history, presenting a privacy concern.
- This extension has low user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/mailfail)