title: What does `mailto:` do when there is no email client?
body: <p>I am developing a website.</p>
  
  <p>What does <code>mailto:</code> open in if there is no email client (like Outlook, Thunderbird, etc.)?
  It works on my computer, which has Outlook, but what if one wants <code>mailto:</code> to open in, say, gmail.com?</p>
  
  <p>What do I need to put in the <code>mailto:</code> statement for that to happen?</p>