SMTP connector getting bombarded.

I have a Microsoft Server 2003 Enterprise edition server running Microsoft Exchange Server 2003 Enterprise edition that has been running fine until the other day. I am receiving tuns of events in the application log, see below. I have added entries in the connection filtering option hoping that this would take care of the problem.

Blacklists

relays.ordb.org
relays.visi.com
bl.spamcop.net
blackholes.wirehub.net
list.dsbl.org

Event viewer info:

This is an SMTP protocol log for virtual server ID 1, connection #5644. The client at "61.31.132.106" sent a "rcpt" command, and the SMTP server responded with "550 5.7.1 Unable to relay for d6358@ms17.hinet.net  ". The full command sent was "rcpt TO:<d6358@ms17.hinet.net>".  This will probably cause the connection to fail.

This is an SMTP protocol log for virtual server ID 1, connection #5645. The client at "61.31.128.104" sent a "rcpt" command, and the SMTP server responded with "550 5.7.1 Unable to relay for stevenlien@seed.net.tw  ". The full command sent was "rcpt TO:<stevenlien@seed.net.tw>".  This will probably cause the connection to fail.


I have not allowed relaying and I have the "filter recipients who are not in the directory" option set.
If anyone has any ideas as to why this is happening, I would greatly appreciate it. This is causing the server to bog down.