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

Purge

Compact Folder, and Delete Junk

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

Compatibility: Thunderbird, Postbox SeaMonkey

Reply to Sender Only

Reply only to the sender of the email

Reply only to the sender of the email.

Compatibility: Thunderbird, Postbox SeaMonkey

Rewrap

Rewrap

Rewraps the message text

Compatibility: Thunderbird, Postbox SeaMonkey

Search Addresses

Open Addresses Search

Open the advanced address search window.

Compatibility: Thunderbird, Postbox SeaMonkey

Send Without Save

Send message without saving a copy

Send message with out saving a copy to the sent folder. If you want this as the permanent behaviour, there is an option in account settings under 'Copies & Folders'

Compatibility: Thunderbird, Postbox SeaMonkey

Copy Email

Copy Email Address to Clipboard

Copy the email address of the currently open email the the clip board.

Compatibility: Thunderbird, Postbox SeaMonkey

Delete Attachments

Delete All Attachments From Message

Delete Attachments from and email.

Compatibility: Thunderbird, Postbox SeaMonkey

Detach Attachments

Detach All Attachments From Message

Detach Attachments from an email.

Compatibility: Thunderbird, Postbox SeaMonkey

Download/Sync Now…

Run download and sync before going offline

Runs the download and sync now tool, so that messages can be used when you go offline.

Compatibility: Thunderbird, Postbox SeaMonkey