Message Composition

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Attach from Clipboard

Create file attachments directly from the system clipboard.

Rated 4 out of 5 stars (30)
5,833 users
Updated March 29, 2025

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 4 out of 5 stars (15)
2,122 users
Updated March 29, 2025

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 contact me

Rated 5 out of 5 stars (13)
5,846 users
Updated March 26, 2025

Antidote connector for Thunderbird

Integrate Antidote with Thunderbird to proofread your emails, check your spelling and grammar, and consult the dictionaries and language guides. Get alerted to abrasive tone and missing attachments before sending a message.

Not yet rated
925 users
Updated March 25, 2025

Signature Switch

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

Rated 4 out of 5 stars (306)
53,281 users
Updated March 24, 2025

Webbuttons - Skype Web

Adds a button in the toolbar for Skype Web. Icon source: https://www.flaticon.com/free-icon/skype_16167326

Not yet rated
19 users
Updated March 23, 2025

Webbuttons - Google Messages Web

Adds a button in the toolbar for Google Messages Web. Icon source: https://www.flaticon.com/free-icon/comment_9449200

Not yet rated
7 users
Updated March 23, 2025

Send Later

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

Rated 5 out of 5 stars (266)
107,680 users
Updated March 19, 2025

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 (49)
3,402 users
Updated March 18, 2025

Grammar, Proofreading & Spell Checker

Check the grammar and spelling directly inside Thunderbird using Wordeep technology

Rated 4 out of 5 stars (4)
673 users
Updated March 16, 2025

HTML Source Editor

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

Rated 5 out of 5 stars (14)
4,505 users
Updated March 14, 2025

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)
22,900 users
Updated March 10, 2025

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)
2,122 users
Updated March 9, 2025

ThunderAI (ChatGPT, Gemini, Ollama in your emails)

ThunderAI uses the capabilities of ChatGPT, Google Gemini or Ollama to enhance email management.
It enables users to analyse, write, correct, assign tags, create calendar events and optimize their emails.

Rated 5 out of 5 stars (17)
4,091 users
Updated March 6, 2025

Owl for Exchange

Allows you to use your Exchange and Office365 email account with Thunderbird using Outlook Web Access (OWA).

Rated 5 out of 5 stars (208)
46,101 users
Updated March 6, 2025

OpenAI Proofreader

This extension uses OpenAI gpt-4o-mini to proofread emails when the user clicks the extension icon.

Usage requires an OpenAI API key. OpenAI does not offer a free usage tier. Proofreading a 4-5 paragraph email costs a fraction of a cent.

Not yet rated
10 users
Updated March 6, 2025

Gemini Proofreader

This extension uses Gemini Flash 2.0 to proofread emails when the user clicks the extension icon.

Usage requires a Gemini API key. There is a free usage tier that should be more than adequate for almost every user.

Not yet rated
10 users
Updated March 6, 2025

ThunderAI Sparks

ThunderAI Sparks is an add-on designed to add advanced features to ThunderAI.

Not yet rated
174 users
Updated March 1, 2025

DS-BCC

Data protection extension, to avoid data mishaps with circular mails:

1. warning for e-mail with multiple recipients not in BCC (exceptions possible)
2. warning for roundmails with a different recipient domain
3. warning if PGP key is present

Not yet rated
78 users
Updated Feb. 25, 2025

regimail

AddOn for sending regimail with Thunderbird on Windows, MacOS and Linux.

*IMPORTANT:*
In order to use this AddOn, you need to install the regify client on your system and configure it with a valid regify account.

Not yet rated
17 users
Updated Feb. 21, 2025