Keeping track of which messages you’ve already read and responded to is a snap if you understand the message icons in your Inbox.
Each time you read, reply or forward a message, Outlook keeps track of the last thing you did by changing the icon to the left of a message displayed in your Inbox.
A new message – one that has not been read.
A message that has been read.
A message that has been read and replied to.
A message that has been read and forwarded.
A message that contains a meeting request.
A message that contains a task request