Off Topic- email notification program

["Monte C. Smith" <mcs@xxxxxxxxxxx>]

 Hi Folks, hope you had a nice Thanksgiving. I sent a few electronic
cards from one of those sites that provides that service. They have an
option that notifies you when the card has been read. So far as I know,
there is no program that has this notification capability unless a
specific server is identified, and that identification is embedded in
the message sent. There are common receipts in most mail programs that
let you know when your message has arrived at its destination address,
but not when it's been read (i.e., opened). Does anyone know what's
involved in this read-receipt process, and what is required to apply it
to all email sent through an ISP? Respond privately, if desired.

Thanks,
Monte