reliable messaging in jabber

http://mail.jabber.org/pipermail/standards/2003-August/003950.html

The only way you can truly do reliable messaging is if the client that
receives the message sends back a confirmation that the message has
been received and processed.

it's still limited to server <-> client reliability, not end to end.

http://mail.jabber.org/pipermail/standards/2003-August/003951.html

I was talking only about transport protocol reliability. Message
tracking is something else and I agree it is a very good idea, but
it is not always needed.