Email Workers Patterns
Parse Email
import PostalMime from 'postal-mime'
export default {
async email(message, env, ctx) {
const buffer = await new Response(message.raw).arrayBuffer()
const email = await PostalMime.parse(buffer)
console.log(email.from, email.subject, email.text, email.attachments.length)
await message.forward('inbox@example.com')
},
}
Filtering
// Allowlist from KV
const allowList = (await env.ALLOWED_SENDERS.get('list', 'json')) || []
if (!allowList.includes(message.from)) {
message.setReject('Not allowed')
return
}
// Size check (avoid parsing large emails)
if (message.rawSize > 5_000_000) {
await message.forward('inbox@example.com') // Forward without parsing
return
}
Auto-Reply with Threading
import { EmailMessage } from 'cloudflare:email'
import { createMimeMessage } from 'mimetext'
const msg = createMimeMessage()
msg.setSender({ addr: 'support@example.com' })
msg.setRecipient(message.from)
msg.setSubject(`Re: ${message.headers.get('Subject')}`)
msg.setHeader('In-Reply-To', message.headers.get('Message-ID') || '')
msg.addMessage({ contentType: 'text/plain', data: 'Thank you. We will respond.' })
await message.reply(new EmailMessage('support@example.com', message.from, msg.asRaw()))
Rate-Limited Auto-Reply
const rateKey = `rate:${message.from}`
if (!(await env.RATE_LIMIT.get(rateKey))) {
// Send reply...
ctx.waitUntil(env.RATE_LIMIT.put(rateKey, '1', { expirationTtl: 3600 }))
}
Subject-Based Routing
const subject = (message.headers.get('Subject') || '').toLowerCase()
if (subject.includes('billing')) await message.forward('billing@example.com')
else if (subject.includes('support')) await message.forward('support@example.com')
else await message.forward('general@example.com')
Multi-Tenant Routing
// support+tenant123@example.com → tenant123
const tenantId = message.to.split('@')[0].match(/\+(.+)$/)?.[1] || 'default'
const config = await env.TENANT_CONFIG.get(tenantId, 'json')
config?.forwardTo ? await message.forward(config.forwardTo) : message.setReject('Unknown')
Archive & Extract Attachments
// Archive to KV
ctx.waitUntil(
env.ARCHIVE.put(
`email:${Date.now()}`,
JSON.stringify({
from: message.from,
subject: email.subject,
}),
),
)
// Attachments to R2
for (const att of email.attachments) {
ctx.waitUntil(env.R2.put(`${Date.now()}-${att.filename}`, att.content))
}
Webhook Integration
ctx.waitUntil(
fetch(env.WEBHOOK_URL, {
method: 'POST',
body: JSON.stringify({ from: message.from, subject: message.headers.get('Subject') }),
}).catch((err) => console.error(err)),
)
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