Most Popular Extensions
Adds tools to import/export messages and folders (NextGen)
Thunderbird v115 Beta Available , Release Shortly
Download Here: Full functionality and very well tested.
Allows bidirectional access to Google Calendar
LookOut decodes winmail.dat (TNEF encoded) files that may come from a misconfigured Microsoft Exchange server or Outlook user allowing access to the original attachments
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.
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
True "Send Later" functionality to schedule the time for sending an email.
Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).
TbSync is a central user interface to manage cloud accounts and synchronize their contact, task and calendar information with Thunderbird.
A new Thunderbird address book based on the CardDAV and vCard standards.
Create and Save or Send Multiple Individual and Personalized Messages from a Draft
Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.
Allows you to use your Exchange and Office365 email account with Thunderbird using Outlook Web Access (OWA).
Switch the signature on/off or choose a new one from your predefined set.
This extension adds support for CalDAV & CardDAV accounts to the Thunderbird Sync manager "TbSync". Including iCloud, ownCloud, Nextcloud, Radicale and many more.
Check your emails for spelling and grammar issues
FileLink provider for WebDAV Featured
Uploads your large attachments to your WebDAV account instead of sending them by email.
Causes Thunderbird's main window to minimize instead of closing. You can still close Thunderbird through the menu.
Securely encrypt and upload large attachments to any Send service instance (formerly Firefox Send).
The best Translator for Thunderbird!
Add sync support for Exchange ActiveSync (EAS v2.5 & v14.0) accounts to TbSync