MailLinter is a free email testing tool that helps developers test emails before sending them to real users. It provides spam analysis with SpamAssassin, WCAG accessibility checking, email client compatibility testing, and AI-powered deliverability scoring using GPT-4o and Claude that synthesizes all results into prioritized actionable fixes.

How do I install MailLinter?

MailLinter can be installed with a single Docker command: docker run -p 2525:2525 -p 8547:8547 nunomsde/maillinter. It takes less than 30 seconds to set up and requires no configuration. Point your application to localhost:2525 for SMTP and open localhost:8547 to view results.

Is MailLinter free to use?

Yes, MailLinter is completely free to use and all features are currently included, including AI analysis (you provide your own API key). An annual license is planned that will unlock premium features like team sharing and login protection. Core email testing will always remain free.

What email clients does MailLinter test compatibility for?

MailLinter tests email compatibility across 15+ email clients including Gmail, Outlook (desktop and web), Apple Mail, Yahoo Mail, Samsung Mail, and more. It covers approximately 95.7% of the email client market share.

DocumentationAI Analysis

AI Analysis

AI-Powered Deliverability Analysis

Name: MailLinter
Availability: InStock
Rating: 4.9 (127 reviews)
Author: MailLinter

AI ingests all your test results—spam scores, accessibility issues, compatibility problems—and synthesizes them into a Deliverability Score with prioritized, actionable fixes.

Why AI Deliverability Analysis?

1 Score

Unified metric from all tests instead of scattered results

Prioritized

Fixes ranked by impact so you know what to fix first

Actionable

Specific fixes you can implement immediately

Supported AI Providers

OpenAI GPT-4o

Advanced model for comprehensive deliverability analysis

Features:

Unified Deliverability Score
Prioritized fix recommendations
Cross-test result synthesis
Impact-based prioritization

What Gets Analyzed

Deliverability Score

Unified score combining all test results into one metric

Weighted spam score analysis
Accessibility impact assessment
Compatibility issue severity
Overall inbox placement prediction

Prioritized Fixes

Actionable recommendations ranked by impact on deliverability

High-impact fixes first
Effort vs impact analysis
Quick wins identification
Critical blockers highlighted

Test Synthesis

Combines spam, accessibility, and compatibility results

Cross-test correlation
Conflict resolution
Holistic issue analysis
Root cause identification

Actionable Solutions

Specific code and content fixes you can implement immediately

HTML/CSS fix suggestions
Content recommendations
Alternative approaches
Best practice guidance

Configuration

Configure your AI provider directly in the MailLinter app. Go to Dev Tools → AI Settings to select your provider and enter your API key.

AI Settings in MailLinter

AI Settings configuration in MailLinter showing provider selection and API key input

Privacy Notice: API keys are stored in memory only and never saved to disk. Email content is sent to the selected AI provider for analysis.

How It Works

Configure AI Provider

Go to Dev Tools → AI Settings and select your preferred AI provider (OpenAI or Anthropic). Enter your API key to enable analysis.

Run Your Tests

Send your email to MailLinter and run spam, accessibility, and compatibility tests as usual.

Click AI Analysis

The AI ingests all test results and synthesizes them into a unified analysis.

Get Your Deliverability Score

Review your overall score and prioritized fixes ranked by impact on inbox placement.