Pros
Open source and customizable: Because Thunderbird is developed by Mozilla, the group behind Firefox, it is more customizable than Outlook, a closed tool developed by Microsoft. At the same time, it offers all of the basics you need right out of the box, so you don't have to worry about highly complicated technical setup if you're not comfortable working in the trenches of a software tool.
Smarter organization: Thunderbird features a range of tools to make organizing your email as easy as possible. Including tabbed email browsing, smart searches, and custom folders to organize your messages, along with powerful spam filters that are better than a lot of Web-based tools, Thunderbird works well with most email services.
Cons
Desktop limitations: Because Thunderbird is a desktop tool for Windows, it doesn't synchronize directly with a mobile device natively. Yes you can set up a POP3 inbox so that all edits in Thunderbird appear at the server level, but it's an extra step that is required with tools like this. It's not unique, and the speed and flexibility of the software makes it a small complaint, but it's something to keep in mind if you compute on your tablet nearly as much as your desktop.
Bottom Line
If you don't like using relatively limited Web-based email tools, or if you'd like to further customize your browsing and organizational experience, Thunderbird is a must download. It's free, it has a number of available plug-ins and updates, and it's a perfect fit for almost anyone with multiple email accounts to manage.
