MailFail

Name: MailFail
Rating: 5 (2 reviews)
Author: Hacks and Hops

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.

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Features & Capabilities

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.

User Growth & Download Statistics

Add-on Privacy & Security Developer Tools

By:

Daily users:

Rating:

Version:

1.0.21 Last updated: 2025-03-04

Version code:

5903862

Creation date:

2024-02-28

Risk:

Permissions:

Size:

527.89KB

URLs:

Website

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-06-16

Compare stats and ranking:

Ranking

# 10,256 ▼ 224

Other rankings

#70 in hotmail keyword 8

#70 in mail keyword 49

#77 in identify keyword 55 ▼ 3

#127 in email keyword 68 ▼ 3

#137 in gmail keyword 71 ▼ 3

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For Developers

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Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.

Developed by:

Hacks and Hops

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/mailfail/

Website:

https://github.com/ACK-J/MailFail

Permission Change History

2024-05-07: Version 1.0.8 → 1.0.9

Add Permissions: storage

Remove Permissions: activeTab

2024-04-18: Version 1.0.7 → 1.0.8

Add Permissions: tabs

Is MailFail Safe?

Risk impact

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

MailFail requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details

Critical Grants access to browser tabs, which can be used to track user browsing habits and history, presenting a privacy concern.
Medium ******* ******* ************* ***** *** ** ******* *** **** ******* ****** ******** *******

Risk likelihood

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

MailFail has earned a fairly good reputation and likely can be trusted.

Risk likelihood analysis details

High This extension has low user count. Unpopular extensions may not be stable or safe.
Low **** ********* *** ******* **** **** * ****** **** ***** ******** *** **** ****** ** ** ****** *** *****
Low **** ********* *** ***** **** **** * ****** **** ***** ********** *** **** ****** ** ** ****** *** *****
Good **** ********* *** **** **** *******