Send Later Requires Restart
True "Send Later" functionality to schedule the time for sending an email.
Create and Save or Send Multiple Individual and Personalized Messages from a Draft
Switch the signature on/off or choose a new one from your predefined set.
Allows you to use your Exchange email accounts that use Outlook Web Access (OWA) with Thunderbird
Check the message contents and addresses before you send the message...
Add emojis to your e-mails.
Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.
A simple button to invoke the (already existing) send later functions.
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.
Flex Confirm Mail Requires Restart
Confirm mail address and attachments based on flexible rules.
Uploads your large attachments to your Box instead of sending them by email.
Grammar Checker Requires Restart
Checks grammar using LanguageTool.
SmartTemplate4 Requires Restart Featured
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 files can now be imported and used directly.
Make your photos smaller, so they don't take forever to email.
Upload large attachments to your Cloud and send the link by email
Identity Chooser helps you to always use the correct identity when composing a new email.
Outlook style headers and few goodies for Thunderbird.
Category manager for Thunderbird contacts, also allows to send an email to all members of a category (categories can be used as contact groups).
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.
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!