Sudden activity on smtp port

From: Michal Jaegermann (michal@gortel.phys.ualberta.ca)
Date: 12/16/02 

From: Michal Jaegermann <michal@gortel.phys.ualberta.ca>
Date: 16 Dec 2002 18:01:29 GMT

On a machine with an MX record pointing somewhere else, and in general
not accepting smtp connections, recently I observe constant attempts to
hook up to this port anyway. It started a bit over a week ago with
packets coming from a machine apparently located in Korea but now it is
all over the map.

Yes, I realize that these are most likely spammers but I thought that
most of open mail relay vanished quite a while ago and tries of that
sort were before very rare. Hence I am a bit puzzled by this sudden
surge in such activity. Some new way to exploit so far unknown weakness
in mail daemons? Any hints or a new info?

  Michal