What does the emoji icon do in the subject line?

What does the emoji icon do in the subject line?

Using emojis in your email subject line can be a smart move to grab the attention of your recipients. It can result in a positive reception, brining in more favorable responses in the form of click and open rates.
To add an emoji in your email subject line,
  1. Click the Emoji icon next to the Subject text box.
  2. Select the emoji you want to use in your subject line.
  3. Click Save.
Learn more about personalizing your email subject line using emojis and merge tags.