随着Firefox 5的到来，Mozilla的邮件客户端Thunderbird也跳过4.0直接已经更新到了5.0版本，这是Thunderbird 18个月后第一次更新主流版本，带来了全新Gecko 5引擎，加入扩展管理器，提升了启动性能，加入可记忆标签，兼容Intel Mac系统，但停止了对PowerPC Mac的支持。
下载:Mozilla Thunderbird 5 - More responsive and faster to start up and use
- Thunderbird is based on the new Mozilla Gecko 5 engine
- New Add-ons Manager
- Revised account creation wizard to improve email setup
- New Troubleshooting Information page
- Tabs can now be reordered and dragged to different windows
- Attachment sizes now displayed along with attachments
- Plugins can now be loaded in RSS feeds by default
- There are several theme fixes for Windows Vista and Windows 7
- Support for Mac 32/64 bit Universal builds (Thunderbird no longer supports PowerPC on Mac)
- Over 390 platform fixes that improve speed, performance, stability and security