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

Thunderbird, Postbox

Forward Inline

Forward the current message as part of the email.

Install Forward Inline

Download Forward Inline

Compatibility: Thunderbird, Postbox SeaMonkey

Get Inbox

Change the currently selected folder to your Inbox.

Install Get Inbox

Download Get Inbox

Compatibility: Thunderbird, Postbox SeaMonkey

Ignored Threads

View all the threads in the current folder that are set as ignored.

Install Ignored Threads

Download Ignored Threads

Compatibility: Thunderbird, Postbox SeaMonkey

Insert

Show Insert Menu

Install Insert

Download Insert

Compatibility: Thunderbird, Postbox SeaMonkey

Message

Show the Message Menu

Install Message

Download Message

Compatibility: Thunderbird, Postbox SeaMonkey

Open in Conversation

Open the current message in a conversation tab

Install Open in Conversation

Download Open in Conversation

Compatibility: Thunderbird, Postbox SeaMonkey

Plain Text Paste

Paste text into Thunderbird without any formatting.

Install Plain Text Paste

Download Plain Text Paste

Compatibility: Thunderbird, Postbox SeaMonkey

Purge

Delete all junk emails then compact all folders. Quick way to do both at the same time.

Install Purge

Download Purge

Compatibility: Thunderbird, Postbox SeaMonkey

Reply to Sender Only

Reply only to the sender of the email.

Install Reply to Sender Only

Download Reply to Sender Only

Compatibility: Thunderbird, Postbox SeaMonkey

Rewrap

Rewraps the message text

Install Rewrap

Download Rewrap

Compatibility: Thunderbird, Postbox SeaMonkey