Send to Trilium

August 16, 2026 · View on GitHub

A Thunderbird MailExtension that imports selected email messages into Trilium Notes through ETAPI. It creates a searchable note per email, optionally preserves attachments and the original message, links the note to its daily note, and skips duplicates.

Disclaimer: Created with help of Claud.ai

Features

  • Thunderbird toolbar action and message-list context menu.
  • Searchable Trilium text note with sender, recipients, sent date, Message-ID and message body.
  • Message body imported as plain text, or as sanitized HTML that keeps the original formatting. You can choose whether remote/external images are kept or stripped.
  • Encrypted messages (PGP/MIME, S/MIME) are detected and skipped rather than imported as unreadable notes.
  • Optional attachment import as child file notes.
  • Optional preservation of the complete original RFC-822 message as a child .eml file.
  • Duplicate detection using a SHA-256 import key derived from the Message-ID (or the raw message when the Message-ID is absent).
  • Configurable date handling: clone the note beneath the matching Trilium daily note, add calendar labels (#startDate/#startTime) so it shows as a calendar event, both, or neither.
  • Optionally give imported notes a color in the tree.
  • Settings page for URL, ETAPI token, destination Note ID and behavior.

The way emails are imported is compatible with those imported using the eml2Trilium addon. That means that if you have imported an email using the eml2trilium widget, and then try to import the same with this addon, it will be detected as a duplicate. This is handy if you cannot run Thunderbird on all your computers.

Requirements

  • Thunderbird 128 or newer.
  • A local TriliumNext Desktop instance, running while emails are imported.
  • A Trilium ETAPI token.
  • A destination note in Trilium under which imported emails will be placed.

This build connects to a local Trilium instance only (localhost or 127.0.0.1).

Setup

1. Configure Trilium

Create an ETAPI token

  1. In Trilium, open Options.
  2. Go to ETAPI.
  3. Create a new ETAPI token and copy it.

Keep the token private — it grants applications access to your Trilium instance.

Create an email archive note

Create a note that will be the parent for imported emails, for example one called Emails. Open the note's information/properties and copy its Note ID (the add-on needs the Note ID, not the title).

2. Install the add-on

Either install the packaged extension, or load it temporarily for testing.

Install from file

Use Thunderbird's Install Add-on From File command and select the packaged extension. A Thunderbird add-on package is simply a ZIP archive of this folder's files; rename it to .xpi if Thunderbird's file picker requires that extension.

Load temporarily (for development/testing)

  1. In Thunderbird, open Add-ons and Themes → Extensions.
  2. Open the gear menu and choose Debug Add-ons.
  3. Choose Load Temporary Add-on and select manifest.json from this folder.

3. Configure the add-on

Open the settings for Send to Trilium from the Add-ons and Themes page.

For a normal local TriliumNext Desktop installation, enter:

Trilium URL:                 http://localhost:37840
ETAPI token:                 <your ETAPI token>
Destination parent Note ID:  <the Note ID of your Emails note>

Click Save and test connection. A successful connection confirms Thunderbird can reach Trilium and that the destination note exists. If localhost does not work, try http://127.0.0.1:37840.

Importing an email

Import from either the message view or the message list: select or open one or more emails, then choose Send to Trilium (from the toolbar action or the right-click menu).

The add-on creates a Trilium note titled with the email subject, containing:

  • sender, recipients and CC recipients;
  • sent date and Message-ID;
  • the message body;
  • the attachment names.

Message body and images

The body is imported either as plain text or, if you choose one of the Original formatting (sanitized HTML) modes, with its layout preserved. All HTML modes remove scripts and keep the email's embedded (inline) images — just as a mail client shows inline images even when external content is blocked. You then choose how remote/external images are handled:

  • Embedded images only — remote images (including tracking pixels) are stripped for privacy and each is replaced by a small placeholder, so the layout stays intact.
  • Allow remote images — remote images are also kept and shown, which means remote content may load when you open the note.

Attachments and the original message

Depending on the settings, attachments are imported as child notes, and the complete original email can be stored as a child .eml file preserving the original MIME message:

Emails
└── Project proposal
    ├── proposal.pdf
    ├── budget.xlsx
    └── Project proposal.eml

The email note itself gets an #email label and an envelope icon (#iconClass=bx bx-envelope). Each attachment child gets an #email_attachment label and the preserved original message gets #file_type=eml, so you can find them with a search.

Encrypted messages

Encrypted emails (PGP/MIME or S/MIME) are skipped instead of being imported as unreadable notes. The completion summary reports how many were skipped.

Date handling

The add-on can associate the email with the date on which it was sent. Available options:

  • Daily note clone + calendar
  • Daily note clone only
  • Calendar only
  • Neither

Daily note clone

When enabled, the imported email is also shown underneath the corresponding Trilium daily note:

Daily Notes
└── 2026-08-15
    └── Project proposal

This is a Trilium clone, not a separate copy: the note under Emails and the note under the daily note are the same note shown in two places. The date is taken from the message's sent date and converted to YYYY-MM-DD in the computer's local timezone; ETAPI obtains or creates the day note and adds a branch for the email beneath it.

Calendar

When enabled, the note receives the calendar's native labels for the day and time the email was sent:

#startDate=2026-08-15
#startTime=13:22

A Trilium calendar view then shows the email as an event at that moment. There is no #endTime (an email has no duration), so the calendar renders it as its default-length block. These labels are also useful for Trilium searches, tables and scripts.

Note color

The settings page has an optional Note color field. Enter a CSS color (for example #3788d8 or teal) and imported emails get a #color label so they stand out in the note tree. Leave it blank for no color.

Duplicate detection

Each imported note gets an emailImportKey label. For messages with a Message-ID, the key is the SHA-256 of the normalized Message-ID; if the Message-ID is absent, it is the SHA-256 of the raw RFC-822 message.

Before creating a note, the add-on searches for an existing note with the same key. If one is found it does not create a second note or duplicate attachments — this prevents accidental duplicates when Send to Trilium is used twice on the same message. It does re-apply the configured date behavior, so enabling daily-note clones later can place an already-imported email beneath the correct day.

For normal use:

Import attachments:        enabled
Preserve original .eml:    enabled
Date handling:             Daily note clone + calendar

This gives you a central searchable email archive, access from the relevant daily note, searchable date metadata, the original attachments, a complete archival .eml copy, and duplicate protection.

Troubleshooting

401 NOT_AUTHENTICATED — Trilium is reachable but the request is not authenticated. Check that the correct ETAPI token is entered in the settings.

NetworkError when attempting to fetch resource — verify Trilium Desktop is running. Open http://localhost:37840/etapi/app-info in your browser; a 401 NOT_AUTHENTICATED response is actually useful here, since it confirms the ETAPI server is reachable. If necessary, try http://127.0.0.1:37840.

Emails are not appearing where expected — check that the Destination parent Note ID points to the intended note. The add-on needs the Note ID, not the note title.

Notes for developers

Host permissions. Firefox/Thunderbird WebExtension match patterns do not include port numbers. Version 0.2.0 incorrectly requested a pattern such as http://localhost:37840/*. Version 0.2.2 requests http://localhost/* (and http://127.0.0.1/*) while continuing to connect to the configured URL, for example http://localhost:37840.

Typical workflow

Receive email in Thunderbird
        ↓
Select "Send to Trilium"
        ↓
Email is stored under "Emails"
        ↓
Attachments and original .eml are preserved
        ↓
Same note appears under the corresponding daily note
        ↓
#startDate / #startTime place it on the calendar and provide date metadata

License

Released under the GNU General Public License v3.0. See the LICENSE file for the full text.