Message Composition

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SubSwitch

Simplify email categorization - it will be easier for you and others to manage mail. Define the set of prefixes for all emails you send or let SubSwitch to autodiscover it. While writing insert prefix to the title - choose one from your set.

Rated 4 out of 5 stars (13)
1,135 users

FlexConfirmMail

Confirm mail address and attachments based on flexible rules.

(This project was renamed from "Flex Confirm Mail" to "FlexConfirmMail", due to a branding reason.)

Rated 4 out of 5 stars (11)
23,144 users

StandardTexter

With the help of this Add-on, up to 99 pre-made texts (standard texts, text modules or even signatures) can be stored, which can then be retrieved and inserted when writing an e-mail.
The texts can be preformatted with HTML.

Rated 5 out of 5 stars (9)
1,896 users

HTML Source Editor

Allows to edit the source of the currently composed message. A simple alternative to ThunderHTMLedit.

Rated 5 out of 5 stars (12)
2,691 users

Shrunked Image Resizer

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

*Shrunked Image Resizer is no longer maintained.*

Rated 4 out of 5 stars (88)
14,411 users

Clippings for Thunderbird

Save frequently-entered text for pasting later.

Rated 4 out of 5 stars (8)
1,575 users

Grammar and Spell Checker — LanguageTool

Check your emails for spelling and grammar issues

Rated 4 out of 5 stars (29)
60,914 users

ReplyWithHeader

Outlook style headers and few goodies for Thunderbird.

Rated 5 out of 5 stars (86)
11,615 users

ReFwdFormatter

Remove the ">" prefix from quote when you make a reply.

[Source code] https://github.com/isshiki/ReFwdFormatter

Rated 4 out of 5 stars (15)
2,294 users

Simple Mail Redirection

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 support page on how to use and why it sometimes does not work!

Rated 5 out of 5 stars (30)
9,055 users

Identity Chooser

Identity Chooser helps you to always use the correct identity when composing a new email.

Rated 4 out of 5 stars (147)
6,456 users

Markdown Here Revival

A revival of the popular Markdown-Here addon for Thunderbird 78 and beyond.

Markdown Here Revival is a Thunderbird extension that lets you write emails in Markdown and render them as HTML before sending.

Rated 4 out of 5 stars (17)
1,587 users

✨ Awesome Emoji Picker ✨

Modern, nice emoji picker that you can use to find and select emojis. It will be copied to your clipboard or even directly inserted into the e-mail, when you click on it.

You will certainly like it.

Rated 5 out of 5 stars (6)
4,858 users

FileLink Provider for Dropbox

Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.

Rated 4 out of 5 stars (20)
54,204 users

Copy Address

Copy email address to clipboard.

Rated 4 out of 5 stars (12)
1,781 users

FileLink provider for Send

Securely encrypt and upload large attachments to any Send service instance (formerly Firefox Send).

Rated 5 out of 5 stars (14)
43,096 users

Folder Account

Lets you associate user accounts and identities with specific folders. Great for multiple users who share TB, or for managing mailing lists.

Rated 4 out of 5 stars (63)
2,138 users

Textmarker

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.)

Rated 5 out of 5 stars (30)
37,672 users

Emoji

It permits just with a single click to copy an emoji.
There is a search-box and the "Most used emojis" section (the first one).

If you want to send feedback or report bug, please go to https://github.com/Sav22999/emoji

Rated 5 out of 5 stars (11)
5,385 users

Emoji

Add emojis to your e-mails.

Rated 4 out of 5 stars (62)
26,029 users