Relaying mail through the servers of a third party is, at best bad
Internet etiquette and, at worst, theft of service.  This is not just
my view but the view of Internet users and service providers
worldwide. Many of the larger ISPs, in a preventative move to stop
their own customers from spamming others, have blocked customer's
connections to any smtp servers but their own.

Open relays, in the vast majority of cases, will not hide the origin
of your message. Your IP address is visible and all traffic is logged.
 
Still not deterred? Okay. Here's one method of finding an open relay:

+ Visit newsgroup <news://news.admin.net-abuse.sightings> and scan
through the posts there looking for any spam reports that mention open
relay, hijack, or relay-rape.

+ Take the mail servers you find in "sightings" and plug them, one by
one, into the form at
<http://vancouver-webpages.com/cgi-bin/nph-chkspam>.

+ If your tests indicate that a particular email server is still an
open relay then your search is over. Insert the mail server's address
in place of your ISP's SMTP server in your email client's
configuration.

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