In your inbox, by the right side of the posts, you can see the date and hour, on which it appeared in the system. Dependent on activities with a post (new comment, response, assigning to another user, postponing) dates and hours can be displayed as follows:

Today's post - only hour will be displayed

Post with a different date than today, but the last update was made today

For example, a client sent you an email yesterday, but you didn't have time to respond or assign it to another user, so you did it today. In this case, in inbox you will see yesterday's date and today's hour of the last update 

Post with a different date and update than today

For example, a week ago you received an email and you've added a comment day later - in this case Sugester will display a date and hour of post's receiving and the last update.

Post with a different than today, no update

You will only see the time and date of receiving the post.