Thunderbird Link Handling with Microsoft Edge Profiles — Seeking Reliable Solution

Thunderbird
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Goal:
I want Thunderbird to open links in my existing Microsoft Edge “Personal” profile, even when other Edge windows are already open and are potentially switched to a different profile.

What I’ve tried:

  • Set network.protocol-handler.warn-external.http and network.protocol-handler.warn-external.https to true in Thunderbird’s Config Editor.

  • Clicked links in emails to trigger the http and https entries under Files & Attachments.

  • Assigned msedge.exe directly as the handler, using:

    Start-Process "C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe" -ArgumentList "--profile-directory=Profile 1", "--new-window", "$url"

  • Also tried compiling the above into an .exe to satisfy Thunderbird’s handler requirements.

Problem:

Even with these flags, Edge:

  • Opens in the wrong profile if another Edge window is already running.

  • Sometimes launches extra tabs (e.g. 0.0.0.1 or startup pages).

  • Ignores --profile-directory unless all Edge processes are closed.

What I don’t want:

  • Using --user-data-dir, which decouples my profile and creates a clone.

  • Using --app, which opens a sandboxed window without my extensions or bookmarks.

Ideal behavior:

  • Thunderbird opens links in my actual “Personal” Edge profile.

  • No need to close other Edge windows.

  • No extra tabs or startup pages.

Question:

Has anyone found a reliable way to:

  • Force Edge to honor --profile-directory even when it’s already running?

  • Use a launcher or script that injects a tab into the correct profile window?

  • Or any Thunderbird-side trick to make this work cleanly?

Any help or insights appreciated!

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I know there have been challenges in this area. My vague recollection is you can’t do what you asking. Our odd collection of bug reports:

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