Whether such an acknowledgment of receipt is sent depends on the configuration of the recipient's email software.
Issuance of a DSN upon delivery failure is the default behavior, whereas issuance of a DSN upon successful delivery requires a specific request from the sender.
However, for various reasons, it is possible for a message to be delivered, and a DSN is returned to the sender indicating successful delivery, but the message subsequently fails to be seen by the recipient or even made available to them.
The DSN SMTP extension, message format, and associated delivery status codes are specified in RFCs 3461 through 3464 and 6522.
A description of how multiple Mail User Agents (MUAs) should handle the generation of MDNs in an Internet Message Access Protocol (IMAP4) environment is provided in RFC 3503.