If you find that your software needs special registry keys called GlitchRetrySeconds, well,
you might need to figure out if you should be writing smtp servers at all.
It seems that if an Exchange 2003 server talks to a server employing blacklisting, it stands a
good chance of "forgetting" about your email until the server is restarted (or smtp is restarted).
Here is a hotfix and a better write up than I can stand to write now:
This dude deserves a medal for not dropping 4 letter words (as I would): (p.s. Thanks
Here is a more complete write-up: