Hi all,
At around 1:40 PM (PDT) my SMTP server started getting flooded

by enormous amount of connections.  The connections were for

seemingly random "users" @my-domain-name.
I'm running spamdb in greylist mode, but these servers were

getting white-listed very quickly.
$ /usr/sbin/spamdb | /usr/bin/grep -c ^WHITE

717
Typical value for above is not more than 20.  Traffic going

in/out of my mail-server is minimal.
I would remove them from the WHITE list and they would fill up

almost immediately.
My guess is someone is using these faked addresses (user@my-domain)

to send out SPAM and I'm getting the bounces from these.
I'm basically looking for opinions as how to combat this problem

right now.  I'm not even 100% on the bounced email theory, but

this had happened to me once before back in May 2003, but the

bounces were mainly from gc.ca domain.
I use gmane to read the list. If not too much to ask, please CC

me on your reply(ies).
Thanks,

--patrick
p.s., Server is running cvs updated -rOPENBSD_4_1 code.