Highlights selected text when composing emails. Default colour is yellow - other colours are available via Options.
(Works only during writing an e-mail, i.e. only in the compose window.)
Allows you to resend (also known as redirect) email messages.
Uses 'cardbook' if installed
Bases on the add-on 'Mail Redirect' by Onno Ekker and Pawel Krzesniak
Please see the help page on how to use and why it sometimes does not work!
Upload large attachments to your Cloud and send the link by email
Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.
Create file attachments directly from the system clipboard.
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.
Uploads your large attachments to your Box instead of sending them by email.
Make your photos smaller, so they don't take forever to email.
It's an extension that changes the format of reply header.
You can choose between the standard Thunderbird reply header, a detailed reply header or a Customized reply header.
You can configure it in the Tools ->Add-on Preferences -> changeQuote.
True "Send Later" functionality to schedule the time for sending an email.
Add emojis to your e-mails.
Identity Chooser helps you to always use the correct identity when composing a new email.
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.
Remembers the language you use with a person or group of people, and switches the spellchecker language automatically for you next time. You do not have to do it manually any more. It remembers and switches it for you.
Category manager for Thunderbird contacts, also allows to send an email to all members of a category (categories can be used as contact groups).
Allows you to use your Exchange email accounts that use Outlook Web Access (OWA) with Thunderbird
Lets you associate user accounts and identities with specific folders. Great for multiple users who share TB, or for managing mailing lists.
Remove nested quotes when replying to a mail.
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!