Section
Protocols
SMTP, IMAP, POP3, MIME: what actually goes over the wire, in real transcripts rather than in metaphors.
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SMTP — the way out
A protocol from 1982 that is readable line by line, if you listen to it.
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Envelope and letterhead
The sender you see is not the sender the server sees. The most consequential distinction in the whole system.
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MIME — everything that is not text
How attachments, accents and HTML got into a protocol that originally knew only 7-bit ASCII.
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IMAP and POP3 — the way back
Two answers to the same question, thought out thirteen years apart — and the difference between them is about where the truth lives.