With the Spark avatars feature, you can breeze through your emails and quickly spot the most important messages. Spark automatically pulls and updates your Inbox with avatars from popular services, your address book, and team members' profiles.
Where do avatars come from? How can I change them?
Spark pulls avatars from multiple sources, and at the moment there’s no option to change avatars right in the app.
Since you are a team member, it is possible to set your own avatar no matter what role you have. All your team members with avatars enabled will see your photo both in the team and in personal conversations.
Spark can also pull avatars from your Gravatar profile. If you are not a team member nor a contact in someone’s address book, Spark will search for your avatar on Gravatar.
Clearbit is used by Spark to pull avatars of different services such as Trello, Jira, Google, etc.