Mail-Tester is a free online tool designed to help email marketers, businesses, and individuals test and improve their email deliverability. It analyzes various aspects of an email (such as content, spam triggers, authentication, and sender reputation) to identify issues that might cause emails to land in spam folders or get blocked.

Key Features of Mail-Tester:

1. Spam Score Check – Detects spammy keywords, poor formatting, or suspicious links that could trigger spam filters.

2. Email Authentication Tests – Verifies whether SPF, DKIM, and DMARC are properly configured to prevent spoofing and improve inbox placement.

3. Blacklist Monitoring – Checks if your sending IP or domain is listed on any spam blacklists (e.g., Spamhaus, Barracuda).

4. HTML & Link Analysis – Examines email structure, broken links, or problematic code that might affect rendering.

5. Reputation Assessment – Evaluates your sender score to gauge how ISPs (like Gmail, Outlook, Yahoo) may treat your emails.

How It Works:

1. Visit Mail-Tester and get a unique test email address.

2. Send an email (or a test campaign) to that address.

3. Return to the site and click “Check your score” to receive a detailed report.

4. Fix issues based on the recommendations to improve deliverability.

Who Should Use It?

• Email marketers optimizing campaigns.

• Businesses ensuring transactional emails (receipts, notifications) reach the inbox.

• Developers & IT teams troubleshooting email setup.

Best of all, it’s free for basic use! (Paid options offer deeper insights for high-volume senders.)