RFC 2822: The Legacy of the Inbox

While modern systems prefer ISO 8601, you will still encounter dates that look like this: `Fri, 05 Apr 2024 15:30:00 +0000`. This is the RFC 2822 format, a legacy standard that remains the foundation of email and several core web protocols.

Origins in RFC 822

RFC 2822 is the successor to RFC 822, which was written in 1982. Back then, the internet was small, and bandwidth was expensive. The format was designed to be easily readable by humans while still being parseable by the primitive computers of the early 80s.

Where You’ll See It Today

• Email Headers: Every email you receive has a `Date:` header formatted according to RFC 2822.
• HTTP Cookies: The `Expires` attribute of a browser cookie must follow this specific format (e.g., `Expires=Wed, 21 Oct 2025 07:28:00 GMT`).
• HTTP Headers: Headers like `Last-Modified` and `If-Modified-Since` almost exclusively use RFC 2822.

The Format Breakdown

Unlike ISO 8601, RFC 2822 is quite verbose:

• Day of Week: A three-letter abbreviation (Fri, Sat, Sun).
• Day: One or two digits.
• Month: Three-letter name (Jan, Feb, Mar).
• Year: Four digits (originally two, but updated to four after the Y2K scare).
• Offset: Often shown as a numeric offset (+0000) or a named zone (GMT).

Conclusion

RFC 2822 is a reminder of the internet’s long history. Even as we move toward more compressed and machine-friendly formats, the "inbox format" remains a living part of the web’s architecture. On the Epoch Clock, we see the future; in RFC 2822, we see the durable legacy of the past.