Received this on an email I sent last night and also on one of two of the BCCs.  Is there any way to find out if and when the mail is delivered or do I need to resend.  As it is a delicate matter of some urgence I am eager for a reply

This is an automatically generated Delivery Status Notification.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

Delivery to the following recipients has been delayed.