These are a ready make selection of some of the most popular buttons from the Custom Toolbar Button Maker

Thunderbird, Postbox

Rewrap

Rewraps the message text

Install Rewrap

Download Rewrap

Compatibility: Thunderbird, Postbox SeaMonkey

Tasks In View

Toggle the Task in View panel in Sunbird.

Install Tasks In View

Download Tasks In View

Compatibility: Thunderbird, Postbox SeaMonkey

Themes

Open the themes manager to change you theme or install a new one.

Install Themes

Download Themes

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Threads with Unread

View only the threads in the current folder that have unread messages.

Install Threads with Unread

Download Threads with Unread

Compatibility: Thunderbird, Postbox SeaMonkey

Toggle Tasks

Toggle the task bar between visible and hidden.

Install Toggle Tasks

Download Toggle Tasks

Compatibility: Thunderbird, Postbox SeaMonkey

Tools Menu

Show the tools menu.

Install Tools Menu

Download Tools Menu

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Unread Threads

View threads that you have not read yet.

Install Unread Threads

Download Unread Threads

Compatibility: Thunderbird, Postbox SeaMonkey