Most Popular Extensions

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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.

Rated 3 out of 5 stars (1,951)
6,518,445 users

ImportExportTools Requires Restart

Adds some tools to import and export folders and messages

Rated 4 out of 5 stars (203)
457,433 users

Provider for Google Calendar Requires Restart

Allows bidirectional access to Google Calendar

Rated 4 out of 5 stars (1,027)
301,035 users

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.

Rated 4 out of 5 stars (300)
166,780 users

Enigmail Featured

OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.

Rated 4 out of 5 stars (224)
128,767 users

Quicktext Requires Restart

Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.

Rated 4 out of 5 stars (327)
90,760 users

gContactSync Requires Restart

Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.

Rated 4 out of 5 stars (268)
88,795 users

CompactHeader Requires Restart Featured

Add symbol in header plane to switch between compact and expanded view. Options to switch between one or two lines compact view, which buttons should be displayed in header pane. New beta version available from http://compactheader.mozdev.org/

Rated 5 out of 5 stars (171)
88,650 users

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

Rated 4 out of 5 stars (29)
85,334 users

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).

Rated 4 out of 5 stars (186)
70,482 users

Send Later Requires Restart

True "Send Later" functionality to schedule the time for sending an email.

Rated 5 out of 5 stars (140)
68,964 users

Signature Switch Requires Restart

Switch the signature on/off or choose a new one from your predefined set.

Rated 4 out of 5 stars (200)
63,429 users

Mail Merge Requires Restart Featured

Mass Mail and Personal Mail

Rated 5 out of 5 stars (162)
60,385 users

LookOut 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).

Rated 4 out of 5 stars (156)
45,252 users

CardBook Requires Restart Featured

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

Twitter: @CardBookAddon

Rated 4 out of 5 stars (191)
40,832 users

Mail Redirect Compatible with Firefox 57+ Featured

Allow to redirect (a.k.a. "remail") mail messages to other recipients.

Rated 4 out of 5 stars (128)
36,013 users

PrintingTools Requires Restart

Adds some options to print messages and addressbooks

Rated 5 out of 5 stars (27)
33,166 users

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...

Rated 4 out of 5 stars (34)
32,749 users

Addressbooks Synchronizer Requires Restart

Synchronizes selected addressbooks with other instances of thunderbird
using ftp/webdav/imap servers

Rated 4 out of 5 stars (59)
32,568 users

Test Pilot for Thunderbird

Add-on has now been discontinued, see below.

Rated 1 out of 5 stars (15)
29,593 users