Multi-brand Email PoC

Send and receive email from multiple domain identities through a single interface. Built on Next.js + Vercel + Brevo + Cloudflare Email Routing. Zero cost to run.

---

Architecture

[Client UI] → [Next.js API on Vercel] → [Brevo SMTP] → recipient
recipient → [Cloudflare Email Routing] → [/api/inbound/receive webhook] → [Postgres]

---

Setup (30-45 minutes)

1. Clone and install

git clone <your-repo>
cd multibrand-email
npm install

2. Database — Vercel Postgres (free)

1. Go to vercel.com → Storage → Create → Postgres
2. Connect to your project — it auto-populates env vars
3. Or use Supabase free tier and copy the connection strings manually

3. Brevo SMTP (free, 300 emails/day)

1. Sign up at brevo.com
2. Go to SMTP & API → SMTP
3. Copy your login email and generate an SMTP key
4. Paste into .env.local as BREVO_SMTP_USER and BREVO_SMTP_KEY

Verify your sender domains in Brevo:

• Go to Senders & IP → Domains → Add a domain
• For each domain (easonet.com, survivalstorehouse.com, etc.), add the SPF/DKIM records they give you

4. Cloudflare Email Routing (inbound, free)

For domains already on Cloudflare:

1. Go to your domain → Email → Email Routing
2. Enable Email Routing — Cloudflare adds MX records automatically
3. Add a catch-all rule: action = Send to a Worker or Forward to your webhook

For domains NOT on Cloudflare — move them, or use ImprovMX:

1. Sign up at improvmx.com (free up to 25 domains)
2. Add your domain, set MX records as instructed
3. Forward all mail to your webhook URL (ImprovMX supports webhook forwarding on paid plan)
   • Alternative: forward to a mailbox, then poll via IMAP (more complex)

5. Configure inbound webhook

Your inbound webhook endpoint is:

https://your-vercel-app.vercel.app/api/inbound/receive

Set a strong random secret:

openssl rand -hex 32

Paste it as INBOUND_WEBHOOK_SECRET in your env vars, and set the same value as the webhook secret header (x-webhook-secret) in your forwarding service config.

Brevo inbound webhook setup:

1. Go to Inbound Parsing in Brevo
2. Set your domain's MX to Brevo's inbound server
3. Point the webhook to your /api/inbound/receive URL

Cloudflare Worker approach (most control): Create a Worker that forwards the raw email to your webhook:

export default {
  async email(message, env) {
    const raw = await new Response(message.raw).arrayBuffer()
    await fetch('https://your-app.vercel.app/api/inbound/receive', {
      method: 'POST',
      headers: {
        'Content-Type': 'message/rfc822',
        'x-webhook-secret': env.WEBHOOK_SECRET,
        'x-forwarded-to': message.to,
      },
      body: raw,
    })
  }
}

6. Deploy to Vercel

npm install -g vercel
vercel

Add all env vars in Vercel dashboard → Settings → Environment Variables.

7. Run database migrations

npx prisma db push

8. Add your first identity

Open the app, click + Add identity, enter name + email. Follow the DNS instructions shown in the modal.

---

Adding a new domain (5 minutes per domain)

1. Add identity in the UI (name + email address)
2. Add domain to Brevo sender verification
3. Set DNS records on the domain:
   • MX: point to Cloudflare Email Routing or ImprovMX
   • SPF TXT: v=spf1 include:_spf.brevo.com ~all
   • DKIM TXT: from Brevo domain verification page
4. Done — emails sent from this identity will appear to come from that domain

---

Migrating to your own infrastructure

When ready to move off free tiers:

Current	Replace with
Brevo SMTP	Postal (self-hosted) or AWS SES
Cloudflare Email Routing	Postfix/Dovecot on a VPS
Vercel Postgres	Supabase Pro or self-hosted Postgres
Vercel API	Node.js on a VPS (same code, npm start)

The API code doesn't change — just swap the env vars.

---

Project structure

/pages
  index.tsx              — email client UI
  /api
    /identities
      index.ts           — GET list / POST create identity
    /emails
      send.ts            — POST send email
      threads.ts         — GET list threads
    /inbound
      receive.ts         — POST inbound webhook
/lib
  prisma.ts              — db client singleton
  mailer.ts              — nodemailer send wrapper
/prisma
  schema.prisma          — Identity, Thread, Message models