Lightning Requires Restart
Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
ImportExportTools Requires Restart
Adds some tools to import and export folders and messages
Provider for Google Calendar Requires Restart
Allows bidirectional access to Google Calendar
Manually sort folders Requires Restart
This extension allows you to manually sort (order) your folders in the folder pane of Thunderbird or automatically sort them, but in a better way. This extension also allows you to re-order accounts in the folder pane.
LookOut (fix version) Requires Restart
LookOut is a plugin which allows Thunderbird to interface with Microsoft's mail tools by decoding metadata and attachments encapsulated/embedded in a TNEF encoded attachment (aka winmail.dat).
Support: Thunderbird and SeaMonkey
Enigmail Requires Restart
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
Quicktext Requires Restart
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
gContactSync Requires Restart
Synchronizes contacts & groups between Thunderbird and Google Contacts.
CompactHeader Requires Restart
Add symbol in header plane to switch between compact and expanded view. New beta versions for the current beta of Thunderbird 68.0 can be found at https://github.com/jmozmoz/compactheader/
Send Later Requires Restart Nabarmenduak
True "Send Later" functionality to schedule the time for sending an email.
Remove Duplicate Messages (Alternate) Requires Restart
Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).
Signature Switch Requires Restart Nabarmenduak
Switch the signature on/off or choose a new one from your predefined set.
Mail Merge Requires Restart
Create and Save or Send Multiple Individual and Personalized Messages from a Draft
CardBook Requires Restart
A new Thunderbird address book based on the CardDAV and vCard standards.
Mail Redirect Requires Restart
Allow to redirect (a.k.a. "remail") mail messages to other recipients.
Display Quota Requires Restart
This extension will display the current status of your IMAP quota in thunderbird's statusbar and will warn you when you reach a configurable limit...
Addressbooks Synchronizer Requires Restart
Synchronizes selected addressbooks with other instances of thunderbird
using ftp/webdav/imap servers
PrintingTools Requires Restart
Adds some options to print messages and addressbooks
Confirm-Address Requires Restart
Stationery Requires Restart
Extension to mimic Outlook Express Stationery.
Allow you to use HTML files as templates for mail. Also allow custom template in replies or forwarded mail!