Restartless Restart

This 15KB restartless add-on will add a "File" -> "Restart" menu item and a ctrl/cmd + alt + r hotkey to restart Firefox or Seamonkey.

google-pagerank

Show Password On Input Requires Restart

Gives an option to show the master password on input

Check Attachment before Send Requires Restart

Confirms to send a mail with any attachment.

One-by-One Forward Requires Restart

Highlight multiple emails, right-click, then select "One-by-One Forward". This extension will allow you to forward the selected emails, one-by-one, to the recipients you specify using your choice of attachment handling.

ConferenceCall.nl templates

Voegt de handige e-mail templates toe aan de knoppenbalk van Thunderbird om deelnemers aan uw conference call uit te nodigen.

QuickFilter Unreplied Requires Restart

Battered with Emails? Need to sort them out? This extension adds a button to the Quick Filter toolbar that shows only unreplied emails. The extension works instantly, just install and look at your Quick Filter toolbar.

Shrunked Image Resizer

Make your photos smaller, so they don't take forever to email.

*Shrunked Image Resizer is no longer maintained.*

DeepL Selected Text

Unofficial DeepL translate extension for Thunderbird.

TbSync

TbSync is a central user interface to manage cloud accounts and synchronize their contact, task and calendar information with Thunderbird.

keepassxc-mail

MailExtension to get password from KeePassXC.

JavaScript Debugger Requires Restart

As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.

Venkman is the code name for Mozilla's JavaScript Debugger. Venkman aimed to provide a powerful JavaScript debugging environment for Mozilla based browsers.

CardBook Featured

A new Thunderbird address book based on the CardDAV and vCard standards.

Twitter: @CardBookAddon

Mailbox Alert

Mailbox Alert allows you to specify, for each seperate mail folder, a message, sound and/or a system command that will be executed when new mail is found there. ...

Lightning Invitation Notifier | LIN

This extension is an extension to Mozilla Lightning for Thunderbird.
It shows a toast message and opens the invitations window when an invitation arrives.

IMAP Quota (Free Space) Requires Restart

This Thunderbird addon lets you customize the IMAP quota statusbar panel.

Provider for CalDAV & CardDAV

This extension adds support for CalDAV & CardDAV accounts to the Thunderbird Sync manager "TbSync". Including iCloud, ownCloud, Nextcloud, Radicale and many more.

Enigmail

Helper tool to migrate your keys and important settings from Enigmail to Thunderbird 78.

Birthday Calendar

Adds calendars containing the birthdays from your address books.

MinimizeToTray revived Requires Restart

Minimizes windows into the system tray.