Read receipt has to enable from admin console for user't to have access of it, you can follow below steps to activate it:
  1. Sign in to admin console
  2. From the dashboard, go to Google Apps > Gmail > Advanced settings.   

  3. If there are suborganizations in the domain, in the Organizations section, highlight your domain or the organizational unit for which you want to configure settings (see Configure advanced settings for Gmailfor more details).

    Note that the Organizations section is not available if no suborganizations have been created
     
  4. In the Email read receipts section, specify which senders your users can return receipts to.

    The default is Do not allow email receipts to be sent, which disables both requesting and returning read receipts.

    You can Allow email read receipts to be sent to any email address, or you can restrict responses to only addresses in your organization and addresses in a white list (see the next step).
     
  5. If you selected Allow email read receipts to be sent to all addresses in my organization as well as the following email addresses, enter any external email addresses to which users can return read receipts.

    Separate email addresses with commas. You can enter up to 100 addresses; each address can have up to 256 characters. If you don't include any addresses, users will only be able to return receipts to other users in your organization.
     
  6. Specify whether to send the receipt automatically or to prompt the recipient to send the receipt.

    If you selected Allow email read receipts to be sent to any email address, users are always prompted for whether to send the receipt, subject to the limitations noted in Returning read receipts. If you restricted the users who can return receipts, you can have Gmail send the receipt automatically when the recipient opens the message; to do so, uncheck the check box Prompt the user for each read receipt request.
     
  7. Click Save changes at the bottom of the screen.

Read receipts are not delivered in the following cases:

  • The message is opened using a POP client or a Google Apps Sync client.
  • The message is opened using an IMAP client, but your administrator has not configured the feature to send receipts automatically.
  • The message is sent to a user through a group mailing list or alias. The message needs to be addressed directly to a user’s email address in order to receive a read receipt from that user.

Request a read receipt (From user end)

If you request a read receipt, requests will be sent to every recipient in the To: and Cc: fields. It does not send a request to recipients in the Bcc: field.

  1. Compose a message as usual while using the desktop version of Gmail at mail.google.com.
  2. Click the More options icon in the compose window.

    Gmail Compose More options screenshot
  3. Click Request read receipt.
  4. Send your message.