This forces the browser to download the latest version of the page instead of using saved files. Google Chrome: Press Command (⌘) + Shift + R . Safari: Press Command (⌘) + Option + R . 2. Refreshing the Desktop or Finder
There is no "Command + R" for Mail. Instead, you can use Command (⌘) + Shift + N to "Get All New Mail".
Sometimes a standard refresh isn't enough because your browser is still loading an old "cached" version of a site. A forces the browser to ignore the cache and download everything from scratch.