Gmail External Email Highlighter

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "Gmail External Email Highlighter",
  "short_name": "External Email Highlighter",
  "description": "For highlighing email addresses in Gmail 'to' fields that don't fit certain rules - ie. that are being sent outside the company.",
  "version": "1.0.1",
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "css": [
        "rulesStyles.css"
      ],
      "js": [
        "runRulesCheck.js"
      ]
    }
  ],
  "permissions": [
    "https://mail.google.com/*",
    "storage"
  ]
}