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''So what happens if I'm running this script and I send an email to you?' I asked innocently '

Or, given how there's zero security in SMTP to prevent forgery (spoofing), what happens if "he" sends an email to "himself"?

I've seen systems spiral themselves into the ground with millions of copies of undeliverable non-delivery-notices (for postmaster) sent to postmaster - and admins who are so clueless they don't know how to clear the spools out, so as soo as they rebooted it just happened again (and again, and again....)