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

Thunderbird, Postbox

Plain Text Paste

Paste Text With No Formatting

Paste text into Thunderbird without any formatting.

Compatibility: Thunderbird, Postbox SeaMonkey

Work Offline

Toggle work offline

Toggle Work Offline and Work Online.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Cut

Cut Selected Text

Cut selected text.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

about:about

List and open any of the about pages

Lists all the "about" pages so that they can be opened.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Filters

Set up Message Filters

Add or edit you current message filters.

Compatibility: Thunderbird, Postbox SeaMonkey

Find

Find Text

Open the find bar to find a word in the current page.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Toolbar Display

Change Toolbar Icon Size and Display Mode

Set the toolbar icon size as either large or small, and the button display mode between icons, icons and text, or text only.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Create Filter

Create filter from message

Create a message filter from the currently selected message.

Compatibility: Thunderbird, Postbox SeaMonkey

Send & Receive

Send and receive messages

Send all messages in the outbox and get all new messages.

Compatibility: Thunderbird, Postbox SeaMonkey

Toggle Read

Toggle Message Read Status

Toggle the Read status of the currently selected message.

Compatibility: Thunderbird, Postbox SeaMonkey