1# Email Workers Patterns
2 
3## Parse Email
4 
5```typescript
6import PostalMime from 'postal-mime';
7 
8export default {
9  async email(message, env, ctx) {
10    const buffer = await new Response(message.raw).arrayBuffer();
11    const email = await PostalMime.parse(buffer);
12    console.log(email.from, email.subject, email.text, email.attachments.length);
13    await message.forward('[email protected]');
14  }
15};
16```
17 
18## Filtering
19 
20```typescript
21// Allowlist from KV
22const allowList = await env.ALLOWED_SENDERS.get('list', 'json') || [];
23if (!allowList.includes(message.from)) {
24  message.setReject('Not allowed');
25  return;
26}
27 
28// Size check (avoid parsing large emails)
29if (message.rawSize > 5_000_000) {
30  await message.forward('[email protected]'); // Forward without parsing
31  return;
32}
33```
34 
35## Auto-Reply with Threading
36 
37```typescript
38import { EmailMessage } from 'cloudflare:email';
39import { createMimeMessage } from 'mimetext';
40 
41const msg = createMimeMessage();
42msg.setSender({ addr: '[email protected]' });
43msg.setRecipient(message.from);
44msg.setSubject(`Re: ${message.headers.get('Subject')}`);
45msg.setHeader('In-Reply-To', message.headers.get('Message-ID') || '');
46msg.addMessage({ contentType: 'text/plain', data: 'Thank you. We will respond.' });
47 
48await message.reply(new EmailMessage('[email protected]', message.from, msg.asRaw()));
49```
50 
51## Rate-Limited Auto-Reply
52 
53```typescript
54const rateKey = `rate:${message.from}`;
55if (!await env.RATE_LIMIT.get(rateKey)) {
56  // Send reply...
57  ctx.waitUntil(env.RATE_LIMIT.put(rateKey, '1', { expirationTtl: 3600 }));
58}
59```
60 
61## Subject-Based Routing
62 
63```typescript
64const subject = (message.headers.get('Subject') || '').toLowerCase();
65if (subject.includes('billing')) await message.forward('[email protected]');
66else if (subject.includes('support')) await message.forward('[email protected]');
67else await message.forward('[email protected]');
68```
69 
70## Multi-Tenant Routing
71 
72```typescript
73// [email protected] → tenant123
74const tenantId = message.to.split('@')[0].match(/\+(.+)$/)?.[1] || 'default';
75const config = await env.TENANT_CONFIG.get(tenantId, 'json');
76config?.forwardTo ? await message.forward(config.forwardTo) : message.setReject('Unknown');
77```
78 
79## Archive & Extract Attachments
80 
81```typescript
82// Archive to KV
83ctx.waitUntil(env.ARCHIVE.put(`email:${Date.now()}`, JSON.stringify({
84  from: message.from, subject: email.subject
85})));
86 
87// Attachments to R2
88for (const att of email.attachments) {
89  ctx.waitUntil(env.R2.put(`${Date.now()}-${att.filename}`, att.content));
90}
91```
92 
93## Webhook Integration
94 
95```typescript
96ctx.waitUntil(
97  fetch(env.WEBHOOK_URL, {
98    method: 'POST',
99    body: JSON.stringify({ from: message.from, subject: message.headers.get('Subject') })
100  }).catch(err => console.error(err))
101);
102```
103