This tips shows the way to identify your mail sent has been successfully received by the recipient.
Step 1) Launch Microsoft Outlook, go to tools, option
Step 2) On the very top right hand side, choose the E-mail Options
Step 3) A new windows will pop up, then select the Tracking Option button
Step 4) Put a check mark on the Request a read receipt for all messages I send button. By doing this, all your mail sent will receive an acknowledgement from the mail recipient once he/she opens the mail. See below for an example of a successful tracking.
A successful tracking will show the mail read time as well as the date of received.