Mozilla recently released version 10 of the popular Thunderbird email client. While Thunderbird works in Windows, Mac and Linux, it’s arguably one of the best free email clients right next to Windows Live Mail on the Windows platform.

Version 10 incorporates the same "add-ons will be compatible as new versions are introduced" way of handling extensions the same way Firefox 10 does now, so what you install will remain compatible as new versions are released.

Here are 5 add-ons that extend Thunderbird in ways that make it a joy to use.

1. ImportExportTools


When you want to export (backup) or import your email, ImportExportTools is absolutely mandatory. You can back up entire folders, batches of messages or even individual messages. Once installed, an import/export is as simple as a right-click on almost any folder or message in MBOX or EML format.

2. Extra Folders Columns


This extension adds in "Unread", "Total" and "Size" columns to the folder columns view. With this installed, you’ll never have to guess how many messages or what the cumulative size of messages are in any folder because it will always be right there to let you know.

3. Show Address Only


Ever wish there was a way to display a column in a message list that shows the email address of the sender or recipient instead of the name? You can in Thunderbird with this extension, as it adds in the column options "Sender[@]" and "Recipient[@]", like this:


Once enabled, that column will show either the sender’s or recipient’s email address instead of the name.

And yes, you can show both name + address in columns right next to each other if you wanted.

4. Stationary


Although the primary purpose of this extension is to mimic the old Outlook Express stationary feature, that’s not the reason I recommend it as a must-have. My reason is that it adds in an "Source (HTML)" tab on composition of new message that allows you to directly edit the formatting code of a message:


On click of tab:


For those that like the ultimate control in fine tuning when composing emails, the Source tab is what makes Stationary worth having installed.

5. MinimizeToTray


This extension adds what most people think should be a mandatory feature – when you click minimize, Thunderbird disappears from the taskbar and only shows as a tray icon next to the clock (clickable to bring the client back to full view).

In addition to being minimize-to-tray, this also optionally double as close-to-tray, so when you click the X at the top right of Thunderbird, the app doesn’t close but rather minimizes to tray the same way it would if you clicked the minimize button. People like this because if you happen to click the close button by mistake when you didn’t really want to close the app, no problem, it’s just minimized.

For those wondering, with this enabled, a true close-of-app would be a simple File / Exit.