Hal Finney says:
Now, my question is, when this mail is delivered to the Unix system which I use, how does the local software know to deliver it to hfinney? My name does not seem to appear in the header at all. In particular, the "To:" address is not hfinney@shell.portal.com, as I would have expected, but rather cypherpunks@toad.com.
All mail has two sets of "To" addresses. There is the ENVELOPE address, which you do not see, and the HEADER address, which is mere window dressing. I could have the headers say "To: That Lousy Schmuck" and the mail would still arrive. The envelope and header addresses have to be kept seperated for all sorts of very sound reasons that I could explain happily in private mail. The envelope address is passed around using the "RCPT" command in SMTP and is never contained in the mail message itself. Perry