A 'deleted unread' receipt tells you that the recipient deleted a copy of the message without marking it Read, it does not guarantee they didn't read it without marking it read.ĭelivery receipts, if supported, will tell you the message made it to the recipient's mailbox. If the recipient reads it using a client that does not support receipts or has an option to not return receipts, you won't get one back. The read receipt only tells you that the recipient marked the message read. Neither receipt option will guarantee you that the message was placed in the Inbox or read. Not all email clients can return read receipts and recipients usually have the option to not return one. Read receipt: send a notification mail when email has been opened by the recipient.Delivery receipt: send a notification mail when the email has been delivered to the mailbox.If you are not familiar with receipts (because Outlook for Mac did not support it), receipts are notification that the message was received or read. The option to request read and/or delivery receipts is on the compose mail Options ribbon and Draft menu.