Message Composition

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Toggle Line Wrap

Toggle wrapping of long lines in the message composition window when writing plaintext messages. Wrapping can be controlled via a toolbar button and a keyboard shortcut.

Rated 4 out of 5 stars (13)
698 users
Updated July 18, 2025

LSP Rewrap

LSP Rewrap cleans up plain-text emails by collapsing extra spaces, tabs, and other spacing issues—like older Thunderbird versions did. Use the toolbar button, Ctrl+Shift+R, or Tools → LSP-Rewrap while composing a plain-text message.

Not yet rated
1 user
Updated July 16, 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 (214)
45,971 users
Updated July 15, 2025

Clippings for Thunderbird

Save frequently-entered text for pasting later.

Rated 4 out of 5 stars (8)
1,950 users
Updated July 15, 2025

AI Mail Support

Add-on designed to enhance email management for both personal and professional use, integrating a set of adanced AI (LLM) features to optimize the email management experience.

Rated 5 out of 5 stars (1)
313 users
Updated July 13, 2025

*cloud - FileLink for Nextcloud and ownCloud Featured

Upload large attachments to your Cloud and send the link by email

Rated 5 out of 5 stars (55)
35,926 users
Updated July 11, 2025

Attach from Clipboard

Create file attachments directly from the system clipboard.

Rated 4 out of 5 stars (33)
5,767 users
Updated July 9, 2025

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 (38)
8,629 users
Updated July 9, 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 (50)
3,248 users
Updated July 5, 2025

Markdown Here Revival

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

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 (18)
1,827 users
Updated July 1, 2025

Autofile - fast e-mail to folder filing

Read an e-mail, hit Autofile button and it is filed / moved to the right mail folder based on the sender's address. No drag/drop needed. Autofile can discover folders to store each author mail. Will save you lots of time like defunct filemail.

Rated 4 out of 5 stars (9)
288 users
Updated June 26, 2025

Daily Reports

This plugin lets you store different profiles with CC, To, Subject and Signature values. Perfect if you need to send emails with similar details often.

Not yet rated
3 users
Updated June 26, 2025

ReplyAgent

Extension for ai generated replys for users emails.

Rated 5 out of 5 stars (1)
6 users
Updated June 25, 2025

Strikethrough Button

Adds a strikethrough toggle button to the Thunderbird compose toolbar. As this is an extension, it is not an integrated component of the Thunderbird toolbar. That is why it sits at the far right on the toolbar and not next to the B/I/U buttons.

Rated 4 out of 5 stars (1)
10 users
Updated June 24, 2025

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 (17)
445 users
Updated June 23, 2025

Text Insert: Templates/Instant Spell Check

Email composer:

*Upper case the first letter of nouns, names, or words at sentence start
*Android(TM) like spellcheck/suggest alternatives (DE, EN, ES, FR,NL)
*Insert styled text, images, tables with shortcuts
*Define shortcut-replacements.

Rated 3 out of 5 stars (7)
230 users
Updated June 23, 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 (18)
2,630 users
Updated June 19, 2025

ThunderAI Sparks

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

Not yet rated
351 users
Updated June 18, 2025

ThunderAI (ChatGPT, Gemini, Ollama in your emails)

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

Rated 5 out of 5 stars (19)
5,618 users
Updated June 18, 2025

TidySubject

Declutter Re:, Fwd:, and EXT tags automatically.

Rated 3 out of 5 stars (2)
14 users
Updated June 17, 2025