When composing the mail, open the Options drop-down menu and select Request Read Receipt. Then, click Send to send the mail.
If you enable the Display Frequently Used Options function, you can choose to add request read receipt right below the edit area.
(1) With the Request Read Receipt feature enabled, a dialog box will appear when the recipient(s) retrieve the mail, asking them if they want to return a read receipt.
(2) Only when the recipient(s) agree to return a read receipt and thus click Yes in the dialog box, will you receive the receipt.
3. Retrieving and Sending Mails-Advanced