4. Content Levels

rawFull  →  raw  →  text  →  clean  →  forAI
                  ↘  html

Level	Description
`rawFull`	Complete RFC 5322 bytes — all headers, MIME parts, encodings. For archival.
`raw`	Latest body only — headers removed, quoted history present, transfer encoding decoded.
`html`	HTML part of latest content. `null` for plain-text messages.
`text`	Plain text of latest content. Derived from `html` if no plain-text part.
`clean`	`text` with quoted reply chains and email signatures removed.
`forAI`	`clean` with whitespace normalised, inline image references removed, forwarded headers collapsed, optional delimiters applied, truncated to `forAIMaxChars`.

The default cleaner detects quoted history using > prefix patterns, On [date] wrote: markers, -----Original Message----- delimiters, and heuristic signature detection (-- RFC 3676 delimiter + trailing short-block patterns). When confidence is low, content is retained.

// Replace the default cleaner
const email = await parse(message, {
  cleaner: (text) => myCustomCleaner(text),   // sync or async
});