Within Teamwork Desk, you can add a public icon to any of your inboxes which will display in the happiness survey form when a customer opens it from an email.
To add a public icon to one of your inboxes, select your profile icon in the top right of your Desk account and choose Settings.
In the Settings area, go to the Inboxes subsection and select the inbox you wish to update.
Once you have then chosen and selected your inbox, from the left pane select Edit Inbox.
You will then see an option to Change Public Icon located under the inbox image.
Click Customize to change the public icon. You can choose from a set of default images or upload your own.
Once you have chosen a public icon for your inbox, this will display in the happiness survey customers receive when you solve a ticket.
If no public image is set, the happiness form will display with no image included.
For more information, see: Enabling Happiness Emails