In a new email message, on the Options menu, in the Tracking group, select the Request a Delivery Receipt check box or the Request a Read Receipt check box. Recipients who occasionally receive a notification that a read receipt is requested on your message are more likely to send a read receipt than if they are prompted every time that they receive a message from you. Tip: As a best practice, consider tracking only single messages of importance instead of all messages.

Under Tracking, select the Delivery receipt confirming the message was delivered to the recipient's e-mail server or Read receipt confirming the recipient viewed the message check box. Request read and/or delivery receipts for all messages that you send There is no way to force a recipient to send a read receipt. There are other scenarios where read receipts are not sent, such as if the recipient's email program doesn’t support read receipts. In Outlook, the message recipient can decline to send read receipts. A read receipt confirms that your message was opened. A delivery receipt confirms delivery of your email message to the recipient's mailbox, but not that the recipient has seen it or read it.

Outlook read receipt response