AgentExtract

Email quote & signature extractor. Given an email's text and/or html, it strips the quoted history — the "On … wrote:" reply chain, forwarded blocks, >-quotes — along with trailing boilerplate noise, leaving just the sender's new content. It's pure string/regex with no DOM parser and no ML, so it runs cheaply on a Lambda Node.js runtime.

AgentExtract is maintained and used by AgentMail.

Install

npm install agentextract

Usage

import { extractEmailBody } from 'agentextract'

const { extractedText, extractedHtml } = extractEmailBody({
  text: 'Sounds good!\n\nOn Mon, Jun 1 Bob <bob@x.com> wrote:\n> old quoted message',
  html: '<div>Sounds good!</div><blockquote>old quoted message</blockquote>',
})
// extractedText === 'Sounds good!'

API

extractEmailBody({ text?, html? }) → { extractedText?, extractedHtml? } is the main entry point. It runs the quote cut and noise-strip on whichever fields you pass; a field that throws is dropped from the result rather than failing the whole call.

The underlying stages are exported too, if you need them on their own:

• extractNewContent(text) / extractFromHtml(html) — the raw cut, before noise-stripping
• stripNoise(text) / stripNoiseHtml(html) — trailing-boilerplate removal
• isTrueDsn(text) — DSN / bounce detection

Attachments

extractAttachment(input) pulls the text out of an email attachment — plain text, HTML, PDF, Word (.docx + legacy .doc), and Excel (.xlsx). It never throws on bad or attacker-controlled input; failures come back as a labeled failed or skipped status. Nested emails (.eml), images/OCR, legacy .xls/.ppt, and archives are out of scope in this version and are skipped.

import { extractAttachment } from 'agentextract'

const result = await extractAttachment({
  content: buffer, // the raw attachment bytes
  filename: 'report.pdf',
  contentType: 'application/pdf',
})
// result.status === 'extracted'
// result.extraction === 'Q3 revenue …'

The heavy parsers (unpdf, mammoth, exceljs, …) are lazy-loaded per handler, so importing extractAttachment costs nothing until you actually call it on a matching attachment. It's also available on its own subpath — import { extractAttachment } from 'agentextract/attachment' — if you want to reach it without touching the body-extraction entry point.

Resource limits & the safety boundary

extractAttachment never throws on hostile input, but its in-process guards are soft — they bound what this library accumulates, not what the OS lets a parser allocate. Treat real CPU/OOM containment as the host's job (a Lambda memory limit, or a terminable worker/subprocess). These guards reduce blast radius; they are not a sandbox.

• Input size — attachments over MAX_INPUT_BYTES (10 MB) are skipped before any decode or parse.
• Decompression — OOXML (.docx/.xlsx) archives are stream-inflated and measured; one that actually expands past MAX_UNCOMPRESSED_BYTES (50 MB) is skipped before the parser loads. Malformed or ZIP64 metadata is treated as over-budget (fail-closed), not trusted.
• Output — extracted text is capped at MAX_OUTPUT_CHARS (250k). The .xlsx and PDF handlers apply this incrementally as they build, so a huge sheet/PDF never materializes in full. The .docx (mammoth) and HTML (html-to-text) handlers return a complete string that is then trimmed — there the cap is post-materialization, so peak memory follows the whole document.
• Timeout — HANDLER_TIMEOUT_MS (10 s) stops awaiting a slow async parse, but cannot cancel synchronous CPU already running inside a parser.
• PDF — page count and accumulated output are bounded (MAX_PDF_PAGES, MAX_OUTPUT_CHARS), but pdf.js's internal per-page decompression is not bounded in-library (no hook exists).

What it does that off-the-shelf engines don't

Benchmarked against TalonJS and Mailgun Talon on a real corpus of ~41k messages (exact-match vs a gpt-4o answer key, graded on the cut):

Capability	AgentExtract	TalonJS	Mailgun Talon
Quote cutting (On-wrote / > / From: / Original-Msg)	yes	yes	yes
Glued "On…wrote:" orphan fix	yes	no	no
Foreign-language attributions (12+ langs) + Chinese/Arabic	yes	limited	limited
DSN / bounce keep-whole	yes	no	no
Forward keep-whole	yes	no	no
Inline-reply keep-whole	yes	no	partial
HTML trailing-signature reattach	yes	no	no
Noise-strip (mobile sigs / disclaimers / footers)	yes	no	no

Per-feature exact-match % (AgentExtract / TalonJS / Talon): on_wrote 96/51/49, no_quote 100/99/99, from_header 89/84/81, gt_quote 85/77/76, foreign_verb 87/61/26, inline 91/38/22, dsn 93/40/40.

Tests

npm install
npm test