0 a message showing that someone has received and opened an email you sent:
1 an automatic answer from someone receiving an email that shows that the message was opened:
Requesting a read-receipt does not guarantee you will get one, as some users disable the function.
Avoid using read receipts - they tell you that the recipient has opened the e-mail but not necessarily that they have read it!
I can't stand people who print every email they get, even the read receipts for emails they sent!
