Up & Coming Extensions
ImportExportTools NG Requires Restart Featured
Adds tools to import/export messages and folders (NextGen)
Allows you to use your Exchange email accounts that use Outlook Web Access (OWA) with Thunderbird
Paranoia Requires Restart
Check if your emails arrived TLS-encrypted (and which corporations were able to read it nevertheless)
Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.
Encrypt if possible Requires Restart
Sets message security option "encrypt message", if valid X509 certificates are found for all recipients.
Grammar Checker Requires Restart Featured
Checks grammar using LanguageTool.
Duplicate Contacts Manager Requires Restart
This Thunderbird add-on searches address book(s) for pairs of matching contact entries.
It can automatically delete entries that have equivalent or less information than the other one.
Any remaining matches are presented for manual treatment.
mailmindr Requires Restart
Follow up for Thunderbird E-Mails. Lightning or other AddOns are not required. Set a reminder by adding a label or by context menu and let mailmindr remind you.
More information on updates and planned features at https://mailmindr.net/
Imap-ACL-Extension Requires Restart
Extension to manage acls/permissions for shared mailboxes/folders on imap servers.
URL Link Requires Restart
URL Link is a small Thunderbird extension that allows you to select a non-URL in a mail/news message or web-page, and open it in a browser window.
AddressBook in Tab Requires Restart
Adds a button that can be put in toolbars which opens the addressbook in a new tab like pastismans AddressBookTab
Lightning Invitation Notifier Requires Restart
This extension is an extension to Mozilla Lightning for Thunderbird.
It shows a toast message and opens the invitations window when an invitation arrives.
BorderColors D Requires Restart
Shows a colorful border around the "New Message" window, so you can tell different identities apart.
Builds on the original BorderColors and the "GT" version, adding different border styles.
Identity Chooser Requires Restart
Identity Chooser helps you to always use the correct identity when composing a new email.
ThreadVis Requires Restart
Displays a small graphic visualising the context (thread) of the currently selected email.
Send Later Button Requires Restart Featured
A simple button to invoke the (already existing) send later functions.
ThunderHTMLedit Requires Restart Featured
Thunderbird HTML editor. This add-on adds a HTML tab to the composition window where you can see and edit the HTML source of the message.
Provider for CalDAV & CardDAV Requires Restart
This extension adds support for CalDAV & CardDAV accounts to the Thunderbird Sync manager "TbSync".
Folder Account Requires Restart
Lets you associate user accounts and identities with specific folders. Great for multiple users who share TB, or for managing mailing lists.
LocalFolders Requires Restart Featured
Add as many local folders as you want to.
New folders can reside on mapped or network locations.
Works with both TB60 through TB68