A message indicating an electronic mail message was not delivered, either because it was misaddressed or a connection failed.

Message sent back to an email sender reporting the message could not be delivered and why. Note: Not all bounced emails result in messages being sent back to the sender. Not all bounce messages are clear or accurate about the reason email was bounced.

Message sent back to an email sender reporting the message could not be delivered and why. Many email systems have their own bounce reasons and there is no set of standards followed by all email servers. The bounce email address is typically defined in the email headers using the X-Sender header.

The message sent back to an e-mail sender reporting the message could not be delivered and why.

A notification message returned to sender indicating that an email message could not be delivered.

A bounce message, or Delivery Status Notification (DSN) message or, simply, a bounce is an automated electronic mail message from a mail system informing the sender of another message about a delivery problem. The original message is said to have bounced.