Message list items should be rendered differently according to message attributes (unread, flagged, replied, etc.).
The JMAP spec specifies the following properties of the message model which should influence the list display:

• isUnread
• isFlagged
• isAnswered
• hasAttachment

These properties shall be translated into CSS classes on the list item. The list item template shall be extended with additional elements displaying icons for the isFlagged, isAnswered and hasAttachment attributes. The isUnread state shall be visualized by displaying the subject and sender with a bold font.

User Story (U 1.1)

• Rob wants to go over the unread messages in his Inbox
• He opens the mail view and clicks the Inbox folder
• He starts scrolling through the Inbox messages
• He identifies unread messages by their bold subject

User Story (U 1.2)

• Santiago usually flags messages he need to go over at a later point
• Now he's ready to review messages requiring his attention
• He opens the Inbox folder and seeks through the list
• He identifies flagged messages by they little flag icon displayed next to the subject