TalkTalk Mail supports Mail Delivery Notifications (MDN).
You select Request read receipt via the compose actions menu prior to sending a mail message.
You can request a read receipt but that does not guarantee that the recipient will acknowledge that request or that the receiving mail service supports Mail Delivery Notifications (MDN).
For example, I can request a read receipt for mail sent to Yahoo! Mail but will never get any acknowledgement because Yahoo! Mail does not support MDN. BT Mail supports MDN and so long as the recipient agrees to send a receipt you'll receive that receipt.
You can test TalkTalk Mail supports MDN by sending yourself a mail message to see exactly what happens.
