But if you are using elm on Unix, try "h" to see the Received header , then you can figure out from which host they have sent the message. Received header is added by smtp hosts on the route, so it's hard to fake. I wrote a very simple automatic junk mailer in ksh long time ago, let me dig it up back at home and send it to you, you can either analyze what smtp is all about or just use it to send junk mails to those jerks.