BirdBox

BirdBox allows you to run desktop Thunderbird on an Android device.

What is BirdBox?

BirdBox is not Thunderbird itself and is not a Mozilla project, but instead is a compatibility layer that sets up a Linux desktop with Thunderbird, launches it, renders it and provides a way to interact with it.

What features does it provide?
Send and receive emails
Mail account setup wizard
Tabbed emails
Search tools
Attachment reminders
Contacts management
Etc

How to Use BirdBox?

Use it just like normal. But here are some specifics to the app.
Tap with one figure to click.
Pinch to zoom.
Slide two fingers up and down to scroll.
If you want to bring up a keyboard, tap on the screen to get a set of icons to appear and then click the keyboard icon.
Hold and slide one finger to pan (useful when zoomed in).
If you want to do the equivalent to a right click, tap with two fingers.
If you want to change the scaling or the dns settings, find the service android notification and click the settings. You have to stop and restart the app after changing these settings for them to take effect.

Why Use BirdBox?

BirdBox is the only way to get Thunderbird on Android. Also desktop Thunderbird has a different set of features than the planned Thunderbird mobile app.

Other tidbits:

BirdBox is fully open source with the source code posted on github: https://github.com/CypherpunkArmory/BirdBox