When your inbox starts filling up, it can start to get a little tricky to stay on top of what you've dealt with and what still needs attention.
To make things easier, responses and replies that haven't been opened are marked with a purple circle:
If you've already opened an interaction, but want to mark it as unread so you or another team member can come back to it later, just click on the three verticle dots next to the response or reply, and hit Mark as unread:
Note: Interactions are marked as read/unread on an organizational level. This means that if a team member opens an interaction, the purple circle will disappear for all members of the organization (whether they have opened it themselves or not). Similarly, if you mark an interaction as unread, all team members will see the purple circle again next to the interaction.