You can view all unread messages in your Conversations Inbox. You can also filter messages to show only unread messages.
View Unread Message
All unread messages have an indicator next to the message. Once a Conversation has been read, the blue dot changes to a gray circle.
Mark as Unread
If you want to mark a Conversation as unread, click the gray circle  so that it displays a blue dot .
Mark Multiple Messages
You can mark multiple Conversations as unread or read by pressing the command key (Mac) or the control key (Windows) while clicking multiple messages, or by selecting the message check box .
Locate and click the settings icon and choose Mark as unread .
If you select multiple unread messages, you will see Mark as read .
Select Unread Conversations
To view only unread messages, open the the Inbox drop-down menu . Select the Unread  link.