Spam Master

About this Add-on

Spam Master brings world-class, real-time spam and threat protection to Thunderbird, powered by one of the top 5 global spam databases. Keep your inbox clean and secure against spam, phishing, malware, and other malicious email threats—no matter if you use POP3 or IMAP accounts.

Blocks millions of known spam emails, domains, IP addresses, and words in real time.
Uses RBL technology (real-time block lists), constantly updated and maintained for highest efficiency.
Protects against junk, scam, phishing, and dangerous attachments before they reach your inbox.
Works seamlessly with all your Thunderbird email accounts.
Lightning-fast: Spam Buffer technology minimizes CPU, memory, and bandwidth use by performing smart local scans—designed for fast email processing.
Includes Whitelist Exemptions for safe emails, domains, and addresses, letting you customize who gets through.
Advanced anti-bot detection and blocks for robotic spam email sources, including those using browser extensions, headless browsers, and automated scripts.
Automated learning: Spam Master continually adapts using daily scan results and user feedback to improve detection and reduce false positives.
Privacy-focused: fully GDPR compliant, no data sharing with third parties.
Comprehensive alert levels, activity statistics, and clean-up tools to keep your protection smart and your Thunderbird smooth.

How it works:

Spam Master scans every incoming email in real time using a global threat database.
Local Buffer technology blocks threats instantly and keeps your inbox safe, even offline.
Whitelist trusted contacts so important messages are never falsely blocked.
Automated logs and detailed statistics provide full transparency on detected threats and blocked messages.

Installation is easy:

Download and install Spam Master for Thunderbird from the official add-ons site.
Open Thunderbird and access Spam Master’s settings from the Add-ons menu.
Customize your protection options and whitelist as needed—everything is ready to use out of the box.

With Spam Master, you can watch your protected message count grow daily and finally enjoy stress-free email. Your inbox has never been safer!

Learn more, see live stats, and view our privacy policy.

Version Information

Version 1.0.6 Released Jan. 28, 2026 83.2 KiB Works with Thunderbird 128.0 and later

## [1.0.6]
### Changed
- Reduced MAX_CONCURRENT_SCANS from 5 to 2 to lower memory usage and improve stability.
- Reduced MAX_SCANNED_IDS from 500 to 200 for more aggressive cache cleanup.
- Increased scan interval from 5 seconds to 15 seconds (SCAN_INTERVAL=15000ms) to reduce resource consumption.
- Added MAX_MESSAGES_PER_SCAN limit (10 messages) to prevent processing too many messages at once.
- Added MAX_MESSAGE_SIZE limit (5MB) - messages larger than 5MB are now skipped to prevent memory spikes.
- Added GC_IDLE_DELAY (100ms) - idle delay after each message to allow garbage collection.
- Rewrote spamMaster_scanUnreadInbox() with IIFE scope isolation for better memory management.
- Applied memory optimization patterns to onNewMailReceived handler with IIFE scope isolation and explicit cleanup.
- Applied memory optimization patterns to context menu handler with IIFE scope isolation and explicit cleanup.
- Deferred body extraction in message_analyzer.js until immediately before API call to reduce memory footprint.
- Deferred body extraction in context_menu.js until immediately before API call to reduce memory footprint.
- Enhanced migration system to handle version jumps correctly with global upgrade tracking flags (spam_master_upgrade_X.X.X) in background/lib/migrate.js
- Improved IP extraction in background/helpers/constants.js to check x-sender-ip header first (most reliable), then extract IPs from both parentheses and brackets in Received headers for better sender IP detection

### Fixed
- Memory leaks in background.js by adding message size filtering, max messages per scan limit, IIFE scope isolation, explicit null assignments for large objects (parts, headers, body), and 100ms idle delays after each message for garbage collection.
- Memory spikes (up to 60MB) during bulk user actions in context menu by deferring body extraction and nulling payload fields after API calls.
- Excessive memory consumption (430MB/hour potential savings) by deferring body extraction in message analyzer until right before API call.
- Failed IP extraction in some cases by enhancing spamMaster_extractIPsReceived() to prioritize x-sender-ip header and extract from parentheses (IP) format in addition to brackets [IP] format in background/helpers/constants.js
- Migration system now properly handles version jumps (e.g., 1.0.3 → 1.0.6) by tracking completed migrations with persistent flags in browser.storage.local in background/lib/migrate.js

### Added
- Explicit memory cleanup after API calls - payload fields (body, headers, attachments) are now explicitly nulled after use to help garbage collection.
- "Rate us" button in options/options-help.html with correct link to Thunderbird Add-ons page (https://services.addons.thunderbird.net/en-US/thunderbird/addon/spam-master/)
- Quick Instructions help table in options/options-help.html explaining: trusted spam filters, Message Filters respect, spam detection tags (orange with fire icon), and whitelist protection (green tags)
- Global upgrade tracking flags (spam_master_upgrade_X.X.X) to ensure migrations run correctly even when skipping versions in background/lib/migrate.js

Source code released under GNU General Public License, version 2.0

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Add-ons

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Spam Master 1.0.6

by SpamMaster

About this Add-on

Version Information

Version 1.0.6 Released Jan. 28, 2026 83.2 KiB Works with Thunderbird 128.0 and later

Add-ons

Welcome to Thunderbird Add-ons.

On the go?

Spam Master 1.0.6

by SpamMaster

About this Add-on

Version Information

Version 1.0.6 Released Jan. 28, 2026 83.2 KiB Works with Thunderbird 128.0 and later

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