As we’ve said before, proprietary software is pricey. Following our list of free and cheap office suites, we now turn to email clients that don’t cost a penny.

Credit: Mozilla
Platforms: Windows, OS X and Linux
- Tabbed windows
- Integration with messaging clients
- Junk mail filter
- Address book
- Supports privacy through Do Not Track
- Protects against phishing
- Add-on library

Credit: SeaMonkey
Platforms: Windows, OS X and Linux
- Integrated mail client, web browser and HTML editor
- Tabbed windows
- Sync across devices
- Session restoration
- Themes
- Open-source
- Junk mail filter
- Multiple accounts

Credit: Citadel
Platforms: Linux and Unix
- Open-source
- Group calendar
- Instant messaging
- Content management with wikis and blogs
- Multiple domain support
- RSS aggregation