Send Later Requires Restart Featured
True "Send Later" functionality to schedule the time for sending an email.
Signature Switch Requires Restart Featured
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
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!
ThunderPEC Requires Restart
ThunderPEC semplifica la gestione della Posta Elettronica Certificata (PEC) e delle comunicazioni PCT e FatturaPA in Thunderbird.
Flex Confirm Mail Requires Restart
Confirm mail address and attachments based on flexible rules.
Check and Send Requires Restart
Check the message contents and addresses before you send the message...
Allows you to use your Exchange email accounts that use Outlook Web Access (OWA) with Thunderbird
Auto Resize Image Requires Restart
Resizer for inline and attachment images (JPEG, PNG, BMP and GIF image formats).
All platforms are supported (Windows, Linux and Macintosh).
Emoji Requires Restart
Add emojis to your e-mails.
SmartTemplate4 Requires Restart
SmartTemplate⁴ offers an easy and powerful way to automatically create customized replies by auto-inserting various mail headers. Templates can be created for every mail identity, Stationery can now be imported and used directly (from 2.3)
Highlighter Requires Restart
Quickly highlight some text in Thunderbird message composing windows.
Send Later Button Requires Restart Featured
A simple button to invoke the (already existing) send later functions.
Shrunked Image Resizer Requires Restart
Make your photos smaller, so they don't take forever to email.
ThunderHTMLedit Requires Restart Featured
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.
Nextcloud for Filelink Requires Restart
"Nextcloud for Filelink" is an Open Source Thunderbird extension which makes it easy to send large attachments with Thunderbird by uploading them first to a Nextcloud server and by then inserting the link into the body of your email.
Automatic Dictionary Requires Restart
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.
ReplyWithHeader Requires Restart
Outlook style headers and few goodies for Thunderbird & Postbox.
CategoryManager Requires Restart
Category manager for Thunderbird contacts, also allows to send an email to all members of a category (categories can be used as contact groups).
Grammar Checker Requires Restart Featured
Checks grammar using LanguageTool.