Message Composition

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Signature Switch Requires Restart

Switch the signature on/off or choose a new one from your predefined set...

Rated 4 out of 5 stars (193)
71,244 users

Send Later Requires Restart

True "Send Later" functionality to schedule the time for sending an email.

Rated 5 out of 5 stars (114)
69,831 users

Mail Merge Requires Restart Featured

Mass Mail and Personal Mail

Rated 5 out of 5 stars (155)
62,306 users

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!

Rated 4 out of 5 stars (106)
34,641 users

ThunderPEC Requires Restart

ThunderPEC semplifica la gestione della Posta Elettronica Certificata (PEC) e delle comunicazioni PCT e FatturaPA in Thunderbird.

Rated 5 out of 5 stars (11)
25,231 users

SmartTemplate4 Requires Restart

SmartTemplate4 offers an easy way to automatically create customized replies by auto-inserting various mail headers. Templates can be created for every account as well as for the default (all email accounts). Also supports the Stationery Add-on.

Rated 5 out of 5 stars (52)
17,986 users

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).

Rated 4 out of 5 stars (30)
16,043 users

Flex Confirm Mail Requires Restart

Confirm mail address and attachments based on flexible rules.

Rated 3 out of 5 stars (3)
14,566 users

Check and Send Requires Restart

Check the message contents and addresses before you send the message...

Rated 4 out of 5 stars (30)
13,675 users

Highlighter Requires Restart

Quickly highlight some text in Thunderbird message composing windows.

Rated 4 out of 5 stars (50)
10,163 users

Emoji Requires Restart

Add emojis to your e-mails.

Rated 5 out of 5 stars (10)
8,763 users

Shrunked Image Resizer Requires Restart

Make your photos smaller, so they don't take forever to email or send to websites.

This extension is not being converted to a WebExtension.

Rated 4 out of 5 stars (33)
8,049 users

Emoji Menu Requires Restart

Adds the ability to easily insert emojis into your composed messages in Thunderbird.

Rated 4 out of 5 stars (8)
5,562 users

Extra Format Buttons Requires Restart

Adds a font size (in pixels), strikethough, subscript and superscript buttons to Thunderbird's Compose Window.

Rated 4 out of 5 stars (12)
5,370 users

Toggle Word Wrap Requires Restart

Toggle word wrapping and PRE element wrapping in the message composition and HTML display windows, respectively.

Rated 4 out of 5 stars (45)
5,159 users

Markdown Here Requires Restart

Write your email in Markdown, then make it pretty. NOTE: This is the legacy XUL version, for Thunderbird, Postbox, Pale Moon, etc. *Not* for modern Firefox; for that use this: https://addons.mozilla.org/en-US/firefox/addon/markdown-here/

Rated 5 out of 5 stars (31)
5,122 users

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.

Rated 3 out of 5 stars (31)
5,024 users

Send Later Button Requires Restart

A simple button to invoke the (already existing) send later functions.

Rated 5 out of 5 stars (1)
4,742 users

Automatic Dictionary

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.

Rated 5 out of 5 stars (34)
4,435 users

BorderColors GT Requires Restart

How many time you sent an email from your wrong email address?
This add-ons allows you assign a different color to the compose window border for each of your email addresses. So you can immediately view from what account are you writing.

Rated 4 out of 5 stars (7)
3,900 users