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

Thunderbird, Postbox

New Event

Add a new event into the calendar.

Install New Event

Download New Event

Compatibility: Thunderbird, Postbox SeaMonkey

New Task

Add a new task to the calendar.

Install New Task

Download New Task

Compatibility: Thunderbird, Postbox SeaMonkey

Previous Message

Get the previous message. Unlink the default Thunderbird buttons this just go to the previous in the list, or if shift is pressed, the previous unread.

Install Previous Message

Download Previous Message

Compatibility: Thunderbird, Postbox SeaMonkey

Read

Open the currently selected message in Thunderbird.

Install Read

Download Read

Compatibility: Thunderbird, Postbox SeaMonkey

Remote Content

Opens the window to set exceptions for the loading of remote content

Install Remote Content

Download Remote Content

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

Toggle Tasks

Toggle the task bar between visible and hidden.

Install Toggle Tasks

Download Toggle Tasks

Compatibility: Thunderbird, Postbox SeaMonkey