How does a spammer hide the destination address?

[blu-Z8efaSeK1ezqlBn2x/YWAg at public.gmane.org (Edward Ned Harvey)]

> From: discuss-bounces-mNDKBlG2WHs at public.gmane.org [mailto:discuss-bounces-mNDKBlG2WHs at public.gmane.org] On
> Behalf Of Tom Metro
> 
> An important thing to realized with SMTP is that the text of the
> ...
> 
> The analogy that is typically used is paper mail, where your email
> (with
> headers) represents the letter, and the addresses exchanged in the SMTP
> transaction represent the information on the envelope. And thus you'll
> hear the terms "envelope sender" and "envelope recipient" referring to
> the SMTP "MAIL FROM" and "RCPT TO" commands respectively.
> 
> etc

Right on.
I was just about to write all that.  Nicely done.

I can write a letter to you Tom, and stick it in an envelope addressed to
Scott.  Scott opens it up, throws away the envelope, and wonders why a
letter to Tom reached his inbox.

The electronic envelope disappears upon mailserver delivery.  Some remnants
are recorded in the message header, which is technically part of the message
body, but not always the ones you wish you had.