Newsletter Digest

Forward newsletters to an Email Routing address and get one digest email per day instead. An email() handler parses each message with postal-mime, summarizes it with Workers AI, and stores it in D1; a daily Cron Trigger sends one digest grouped by sender via the send_email binding.

FeaturesCopy Anchor Link

• Inbound email() handler with postal-mime parsing; messages over 1 MB are rejected
• Optional ALLOWED_SENDERS allowlist (addresses or domains), checked against both envelope sender and From header
• HTML-only newsletters are stripped to plain text before summarizing
• 2–3 bullet summaries from @cf/meta/llama-3.1-8b-instruct-fast, falling back to the first 300 characters if AI fails
• First non-unsubscribe link kept as a "Read more" link
• Daily digest (text + HTML) grouped by sender; items are marked digested only after the send succeeds

API ReferenceCopy Anchor Link

GET /itemsCopy Anchor Link

List the latest 100 items, newest first.

pending "true" | "false" (optional)

true returns only items not yet included in a digest.

curl "https://your-worker.workers.dev/items?pending=true"

{
  "count": 1,
  "items": [
    {
      "id": 7,
      "from": "news@example.com",
      "fromName": "Example News",
      "subject": "Issue #42",
      "summary": "- Big launch this week\n- Pricing changes in November",
      "link": "https://example.com/42",
      "receivedAt": "2026-10-01T05:12:00.000Z",
      "digestedAt": null
    }
  ]
}

POST /digest/previewCopy Anchor Link

Build the digest from pending items (up to 100) without sending or marking anything.

curl -X POST "https://your-worker.workers.dev/digest/preview"

{
  "subject": "Newsletter digest 2026-10-01: 1 item",
  "text": "Newsletter digest 2026-10-01: 1 item\n\n== Example News <news@example.com> ==\n\nIssue #42\n  - Big launch this week\n  - Pricing changes in November\n  https://example.com/42",
  "html": "<!doctype html><html>...</html>",
  "itemCount": 1,
  "senderCount": 1
}

POST /digest/sendCopy Anchor Link

Send the digest now to DIGEST_TO and mark the included items digested. Requires Authorization: Bearer <ADMIN_TOKEN>.

curl -X POST "https://your-worker.workers.dev/digest/send" \
  -H "Authorization: Bearer $ADMIN_TOKEN"

{ "sent": true, "itemCount": 1, "messageId": "..." }

When nothing is pending, the response is { "sent": false, "itemCount": 0 } and no email is sent.

Error CodesCopy Anchor Link

• 400 - INVALID_QUERY (bad pending value), MISSING_CONFIG (DIGEST_TO not set)
• 401 - UNAUTHORIZED
• 502 - SEND_ERROR (Email Sending rejected the digest; items stay pending)
• 500 - INTERNAL_ERROR

ArchitectureCopy Anchor Link

newsletter → Email Routing (digest@yourdomain.com) → email() handler
  ├─ > 1 MB → setReject
  ├─ sender not allowed → ignored
  └─ postal-mime → text / html→text → Workers AI summary → D1 items (digested_at NULL)

cron 0 7 * * * → pending items → group by sender → send_email → digested_at = now

Use CasesCopy Anchor Link

• Cut a dozen daily newsletters down to one email
• Learn the inbound email() handler, Workers AI, D1, Cron, and Email Sending together
• Starting point for any "collect mail, process later" pipeline (receipts, alerts, reports)

LimitationsCopy Anchor Link

• GET /items and POST /digest/preview are public; put them behind Cloudflare Access or add the admin check if summaries are sensitive
• HTML-to-text is regex-based and rough on complex layouts; only the first 6000 characters are sent to the model
• Link extraction picks the first non-unsubscribe link, which may be a header or sponsor link
• One digest holds at most 100 items; the rest go in the next run
• Messages are processed one at a time in the email() handler, so the AI call adds latency to delivery

Use in your projectCopy Anchor Link

npm install postal-mime

const NAMED_ENTITIES: Record<string, string> = {  amp: "&",  lt: "<",  gt: ">",  quot: '"',  apos: "'",  nbsp: " ",  mdash: "—",  ndash: "–",  hellip: "…",  rsquo: "’",  lsquo: "‘",  rdquo: "”",  ldquo: "“",};const SKIP_LINK = /unsubscribe|preferences|manage[-_ ]?subscription|view[-_ ]?in[-_ ]?browser/i;function decodeEntities(text: string): string {  return text.replace(/&(#x[0-9a-f]+|#\d+|[a-z]+);/gi, (match, entity: string) => {    if (entity[0] === "#") {      const code =        entity[1] === "x" || entity[1] === "X"          ? Number.parseInt(entity.slice(2), 16)          : Number.parseInt(entity.slice(1), 10);      return Number.isFinite(code) && code > 0 && code <= 0x10ffff        ? String.fromCodePoint(code)        : "";    }    return NAMED_ENTITIES[entity.toLowerCase()] ?? match;  });}/** Deliberately simple: good enough to feed an LLM, not a faithful renderer. */export function htmlToText(html: string): string {  const text = html    .replace(/<!--[\s\S]*?-->/g, "")    .replace(/<(head|style|script|noscript|title)\b[^>]*>[\s\S]*?<\/\1>/gi, "")    .replace(/<br\s*\/?>/gi, "\n")    .replace(/<li\b[^>]*>/gi, "\n- ")    .replace(/<\/(p|div|h[1-6]|ul|ol|tr|table|blockquote|section|article)>/gi, "\n")    .replace(/<[^>]+>/g, "");  return decodeEntities(text)    .replace(/[\u200b-\u200d\ufeff\u034f]/g, "")    .replace(/[ \t\f\v\u00a0]+/g, " ")    .replace(/ *\n */g, "\n")    .replace(/\n{3,}/g, "\n\n")    .trim();}export function extractFirstLink(html: string | undefined, text: string): string | null {  const candidates: string[] = [];  if (html) {    for (const match of html.matchAll(/<a\b[^>]*\bhref\s*=\s*["']([^"']+)["']/gi)) {      candidates.push(decodeEntities(match[1]));    }  }  for (const match of text.matchAll(/https?:\/\/[^\s<>()"']+/g)) {    candidates.push(match[0]);  }  return candidates.find((url) => /^https?:\/\//i.test(url) && !SKIP_LINK.test(url)) ?? null;}

DeploymentCopy Anchor Link

npx wrangler d1 migrations apply newsletter-digest-db --remote
npx wrangler secret put ADMIN_TOKEN

npx wrangler email sending enable yourdomain.com

curl "https://your-worker.workers.dev/items?pending=true"
curl -X POST "https://your-worker.workers.dev/digest/preview"

Local DevelopmentCopy Anchor Link

cd apps/experiments/newsletter-digest
npm install
npx wrangler d1 migrations apply newsletter-digest-db --local
npx wrangler dev --test-scheduled

Simulate an inbound email, then preview and trigger the cron:

curl -X POST "http://localhost:8787/cdn-cgi/handler/email?from=news@example.com&to=digest@example.com" \
  --data-binary $'From: Example News <news@example.com>\r\nTo: digest@example.com\r\nSubject: Issue 1\r\nContent-Type: text/plain\r\n\r\nBig news this week. https://example.com/1'

curl -X POST "http://localhost:8787/digest/preview"
curl "http://localhost:8787/__scheduled?cron=0+7+*+*+*"

ConfigurationCopy Anchor Link

wrangler.json declares:

• Workers AI AI
• D1 DB (migrations/0000_init.sql creates items)
• send_email binding EMAIL
• Cron 0 7 * * *
• Vars DIGEST_FROM, DIGEST_TO, ALLOWED_SENDERS (comma-separated addresses or domains; empty accepts all)

Secret: ADMIN_TOKEN. Dependency: postal-mime.

Cloudflare Features UsedCopy Anchor Link

• Email Routing / Email Workers - Inbound email() handler
• Workers AI - Newsletter summaries
• D1 - Item storage and digest state
• Cron Triggers - Daily digest
• Email Sending - Digest delivery via send_email