Open the Marketing tab from your Dashboard.

Select Email Campaigns.

Then, select the Email Campaign you wish to edit.

Open your Text Block with the Email Visual Editor or click into your text editor with the classic editor.

Simultaneously press:

For Mac Users: Command + Control + Spacebar

For Windows Users: Windows + . (period)

For Linux Users: Ctrl + . (period)

Select the emoji you would like to include and continue customizing your email.

Be sure to click Save to keep your changes: