Do you want to know if the sender requested a return receipt before you open the mail and the receipt is sent?
Put these 2 lines in the untitled attachment column in your mail template's Inbox folder:
When a mail with return receipt request comes, you will see an open envelope icon in the attachment column next to subject. Once you open the mail, the return receipt is sent and icon disappears.
If you don't want to send a return receipt (to a spammer, for example) delete the mail in the view without opening it.