"Nuts & Volts Magazine"their url is
http://www.nutsvolts.com
the article is on page 43 and titled
"Cyber Street Survival"
they cover a product called
net demonwhich can be gotten for $20, i think its share ware and you can get a trial copy for free. but hey i have lied before. it refers to 2 urls i think one of them is a mis print
http://www.netdemon.net
http://www.netdemon.org
it looks like it gives DOS machines tools like PING, TRACEROUTE, WHOIS, ....
on page 46 they cover how to verify if a email address is valid. from the text it looks like netdemon invokes sendmail on the remote machine or local host and uses it to verify the address for you.
also a few related urls he talks about are
http://www.samspade.org
http://www.netdemon.net
http://www.netdemon.org
http://www.nutsvolts.com
http://www.neoworx.com
http://www.fusionsites.com
http://www.visualware.com
http://www.visualware.com/visualroute/index.html
http://www.visualware.com/visualroute