http://jqyzxhjk6psc6ul5jnfwloamhtyh7si74b4743k2qgpskwwxrzhsxmad.onion/docs/faq-abuse.html.en
In short, Tor isn't useful for spamming,
because nearly all Tor relays refuse to deliver the mail. Of course, it's not all about delivering the mail. Spammers can use
Tor to connect to open HTTP proxies (and from there to SMTP servers); to
connect to badly written mail-sending CGI scripts; and to control their
botnets — that is, to covertly communicate with armies of
compromised computers that deliver the spam.