Examine source code of Email Notifier

{
  "version": "0.2.3",
  "manifest_version": 3,
  "name": "Email Notifier",
  "homepage_url": "https://mybrowseraddon.com/email-notifier.html",
  "description": "A lite notifier that works with Gmail™, Yahoo, Live, iCloud, and more.",
  "commands": {
    "_execute_action": {}
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "data/options/options.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "109.0",
      "id": "jid1-iqxEAwQsa3GZKc@jetpack"
    }
  },
  "permissions": [
    "alarms",
    "storage",
    "webRequest",
    "notifications",
    "declarativeNetRequest"
  ],
  "host_permissions": [
    "*://*.gmx.com/*",
    "*://*.live.com/*",
    "*://*.mail.com/*",
    "*://*.zoho.com/*",
    "*://*.tuta.com/*",
    "*://*.proton.me/*",
    "*://*.yahoo.com/*",
    "*://*.icloud.com/*",
    "*://mail.google.com/*"
  ],
  "action": {
    "default_title": "Email Notifier",
    "default_popup": "data/popup/popup.html",
    "default_icon": {
      "16": "data/icons/16.png",
      "32": "data/icons/32.png",
      "48": "data/icons/48.png",
      "64": "data/icons/64.png"
    }
  },
  "content_scripts": [
    {
      "all_frames": true,
      "run_at": "document_start",
      "js": [
        "data/content_script/inject.js"
      ],
      "matches": [
        "*://*.gmx.com/*",
        "*://*.mail.com/*"
      ]
    }
  ],
  "background": {
    "scripts": [
      "lib/config.js",
      "lib/chrome.js",
      "lib/runtime.js",
      "lib/netrequest.js",
      "lib/webrequest.js",
      "lib/emails/gmx.js",
      "lib/emails/zoho.js",
      "lib/emails/live.js",
      "lib/emails/tuta.js",
      "lib/emails/yahoo.js",
      "lib/emails/gmail.js",
      "lib/emails/proton.js",
      "lib/emails/icloud.js",
      "lib/emails/mailcom.js",
      "lib/vendor/from-xml.js",
      "lib/common.js"
    ]
  },
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  }
}