title: How do I get an icon in Google Inbox?
body: <p>I receive e-mails from various senders, and when I view them in Google Inbox, either on inbox.google.com, or on the Android App, some have an icon in a circle next to them... others just have a letter.</p>
  
  <p>BitBucket, for example, has a nice icon when they send me an e-mail:
  <a href="https://i.stack.imgur.com/44EoV.png" rel="noreferrer"><img src="https://i.stack.imgur.com/44EoV.png" alt="BitBucket icon"></a></p>
  
  <p>The question:</p>
  
  <p>Does Google Inbox fetch this picture with some kind of G+ magic, or are certain e-mail headers involved here?</p>
  
  <p>How do I implement this in my own solutions when sending out e-mails?</p>