This tutorial will show you how to Request Read Receipts.
When you request a read receipt for an outgoing email, the recipient will receive the following message: "The sender has requested that a read receipt be sent when this message is read. Do you want to send a receipt? Yes | No". The recipient has a choice to accept by clicking yes, or decline by clicking no.
Keep in mind, not all other email providers and apps support read receipts, so read receipts are not 100% reliable. Most popular email services do support and return read receipts, but in some cases the recipients will not be configured for this feature and you will not receive a read receipt when they open the message.
Requesting a read receipt for a single outbound message
Compose a new message, click the Action menu and select Request Read Receipt
Request read receipts by default for all outbound messages
Step 1: Go into Settings from the More dropdown menu.
Step 2: In the Webmail tile, toggle right to enable Request read receipts by default
Step 3: Click Save