shutting out an IP

[Paul Tod Rieger <prie@abl.com>]

Shortly after I stop seeing the bootp/dhcp messages on my cable network,
I start getting:

Apr 27 22:20:15 www tcplogd: smtp connection attempt from
unknown@ATHM-209-218-xxx-206.Home.net [209.218.141.206]

Apr 27 22:20:15 www in.smtpd[10502]: warning: /etc/hosts.deny, line 15:
can't verify hostname: gethostbyname(ATHM-209-218-xxx-206.Home.net)
failed

Apr 27 22:20:15 www in.smtpd[10502]: refused connect from
209.218.141.206

repeatedly -- every 5 seconds -- for about 12 hours.  (Maybe they
stopped because the sender had to go to school.)

What are some ways to stop this in real-time?  I've e-mailed
abuse@home.net and added the IP to /etc/hosts.deny -- do I need to tell
the system to reread that file?  Anything else?

Thanks for any info!

Tod