If I get a message that required a read reciept, and click delete and "Do not send Read Receipt", it sends a damn message to the sender saying I deleted the message without reading it. W - T- F. Just noticed this by sending a message to myself through another account, and deleting it without reading.
Now, if a spammer sends out a few million messages to random email addresses with a "request read receipt", he's going to get back which email addresses are valid.
Now, if a spammer sends out a few million messages to random email addresses with a "request read receipt", he's going to get back which email addresses are valid.