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).
Create and Save or Send Multiple Individual and Personalized Messages from a Draft
True "Send Later" functionality to schedule the time for sending an email.
Switch the signature on/off or choose a new one from your predefined set.
MEGAbird Requires Restart
Add MEGA support to Thunderbird's Filelink feature.
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.
Add emojis to your e-mails.
Check the message contents and addresses before you send the message...
SmartTemplates 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 files can now be imported and used directly.
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.
Confirm mail address and attachments based on flexible rules.
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.
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.
Markdown Here Requires Restart
Write your email in Markdown, then make it pretty.
Category manager for Thunderbird contacts, also allows to send an email to all members of a category (categories can be used as contact groups).
Emoji Menu Requires Restart
Adds the ability to easily insert emojis into your composed messages in Thunderbird.
Make your photos smaller, so they don't take forever to email.
Grammar Checker Requires Restart
Checks grammar using LanguageTool.
Outlook style headers and few goodies for Thunderbird.