How to change default web browser for links in Mozilla Thunderbird

This example is for Microsoft Windows. Links opened directly in Microsoft Edge.

To change the default web browser which is opened when clicking a link inside Mozilla Thunderbird, edit the file "handlers.json" inside your Thunderbir profile, for example "%APPDATA%/Thunderbird/abcdef12.default-release".

My file had the default content:

{"defaultHandlersVersion":{},"mimeTypes":{"application/pdf":{"action":3,"extensions":["pdf"]}},"schemes":{"https":{"action":4}},"isSVGXMLAlreadyMigrated":true}

Which I changed to this:

{
  "defaultHandlersVersion": {},
  "mimeTypes": {
    "application/pdf": {
      "action": 3,
      "extensions": [
        "pdf"
      ]
    }
  },
  "schemes": {
    "https": {
      "action": 2,
      "handlers": [
        {
          "name": "chrome.exe",
          "path": "C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe"
        }
      ]
    },
    "http": {
      "action": 2,
      "handlers": [
        {
          "name": "chrome.exe",
          "path": "C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe"
        }
      ]
    }
  },
  "isSVGXMLAlreadyMigrated": true
}

Now is possible to see the new entries for "http" and "https" in section Settings -> Files & Attachments, which was not available before, and make further modifications from there:

For Linux, macOS, FreeBSD, etc. just adjust accordingly.

Make sure Thunderbird is closed when performing this operation.

Links:

• Open links from Thunderbird with non-default browser