Add-ons
Newest Extensions
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AutoCopy Send
Adds an extra Send button to the compose window that automatically copies the message to a configured list of CC and/or BCC addresses (e.g. a CRM logging address, a team archive mailbox, or a manager).
Addy.io Recipient Converter
Converts recipients using the identity reply-to address on send to the format required by addy.io. If the reply-to field is empty, does nothing. If populated, transforms recipient address(es) (i.e. TOs, CCs, and BCCs) based on the reply-to address.
Safe Trash Cleaner
Empties trash, junk and selected folders of selected Thunderbird accounts after confirmation.
Drop Attachment 拖放添加附件
Drag and drop files from your file manager directly into the compose window to add them as attachments.
从文件管理器或桌面直接将文件拖拽到写邮件窗口中，即可将其添加为附件，无需再点击附件按钮逐级查找文件。
Reviewed-by button
A Thunderbird MailExtension that adds an `R-b` button to the compose window and inserts a `Reviewed-by:` line for the currently selected sender identity at the current cursor position.
Undo Send Notification
Delays sending an email and provides a notification to undo it.
VFS-Provider: OneDrive
A VFS provider add-on that enables WebExtensions using the VFS Toolkit to access files on a OneDrive folder.
LLM Chat Cleaner
Delete all conversations from ChatGPT, Claude, Grok, Gemini, Perplexity, and DeepSeek
Retyc
Encrypt and upload large files with to Retyc. Recipients with a Retyc account get E2E encryption; others access files using a passphrase.
FileLinkKekUpload
A simple extension to upload attachment files to your KekUpload (https://github.com/GamePowerX/KekUploadServer) instance.
MailStone for Thunderbird
Certify your emails on the blockchain directly from Thunderbird. Legal-grade, eIDAS-qualified proof — without changing your workflow. Add the certification BCC address to your compose window in one click.
mleak - mail metadata osint
mleak is a Thunderbird extension for per-mail osint header and body analysis. MUA fingerprints, server stack, M365 tenant data,relay path, auth verdicts and integrity signals.
100 % offline. No network access, no telemetry, no external dependencies.
Attachment Optimizer
Automatycznie kompresuje obrazy (→ WebP) i skany PDF przed wysłaniem. Obsługuje drag &
drop, przekazywanie wiadomości oraz wstawianie obrazów inline.
FileLink Provider for PsiTransfer
Use Thunderbird FileLink with your own self-hosted PsiTransfer server to upload attachments and share links. You must provide the URL of your own PsiTransfer server in the add-on settings. This add-on does not include hosting.
SoundMail
Thunderbird add-on: play different new-mail sounds using rules (sender, domain, subject, body, regex), per-account & default sounds, drag-to-reorder priority, JSON import/export, and optional light/dark theme + UI language for the settings page.
Quote without ..
Reply with quote without useless things (strip off images, signatures or old messages).
Minimal extension made after considering environmental impact of the size of exchanged mails between people.
Simple options. No unnecessary permission.
NestorAI
NestorAI is an AI assistant for Thunderbird that helps analyze email, prepare reply drafts, organize messages, and generate recaps, while also supporting local AI so processing can stay on the user's machine.
WashiBird
A cozy, paper-like theme (Light/Dark). Built as an extension to allow deeper UI customization than standard themes support.
KIM Attachment Search
Sucht in KIM-Anhängen (XML/PDF/DOCX) und zeigt Meta-Daten
To create your own collections, you must have a Mozilla Add-ons account.
