Edit Message Encoding Fallback Requires Restart
Fallback to a safe encoding, if you are replying to a message with unsupported encoding like UTF-16LE. (workaround for the Bug 961983)
Google Keep for Thunderbird
Logout Requires Restart
This extension adds "Logout" to the folders context menu.
After you "Logout" you will be asked again for passwords for this account (incoming and outgoing).
JIRA Integration Plugin (Beta) Requires Restart
Create Jira Tickets directly from within Mozilla Thunderbird (based on E-Mails). This Addons saves your Username and Password in clear text. Use on your own risk. (Also, you might need to disable the CSRF Filter in your JIRA Instance.)
This add-on offers ui tweaks to improve Thunderbirds appearance (squared tabs, custom tab height, alternative Add-on Manager appearance, compact main toolbars and more). v2.0.5+ for Tb52-61+
Zoiper Thunderbird Plugin Requires Restart
It allows you to make calls via Zoiper from Mozilla Thunderbird.
Quick Locale Switcher 2 Requires Restart
Allows you to quickly switch to a different language (User Interface, Spell Checker Dictionary and Website content) in your Mozilla application.
Attach from Clipboard Requires Restart
Create file attachments directly from the system clipboard.
Reply As Original Recipient Requires Restart
Reply with the From: field set to the To: field from the original email.
Reply To All Reminder Requires Restart
Asks for confirmation when "Reply" instead of "Reply to All" is pressed on an email with multiple recipients.
SMTP Switch Reborn Requires Restart
Thunderbook Requires Restart
Export messages (including RSS items) as e-books.
Checkbox Column Requires Restart
Adds a custom column to Thunderbird's messages list (thread tree), making it easier to select multiple messages on devices with a touchscreen display.
Reinstates the extensions.checkCompatibility preference.
Stego Block Requires Restart
Embeds a small secondary, encrypted message in an email, known as a Stego Block.
Image Zoom (ugly fixes) Requires Restart
An ugly attempt at fixing Image Zoom
AastraClickToCall Requires Restart
Converts telephone numbers into clickable links for use with Aastra IP Phones
MultiTemplateLoader Requires Restart
Manages & applies multiple HTML templates when creating/replying messages.
Templates may be either local files or online links (http:// or ftp://). Up to 9 templates can be defined and easily switched, also using shortcut keys.
Identity Checker Requires Restart
This add-on checks to sender identity when send a message.
Layout Button Requires Restart
A toolbar button to switch between layouts.