MailingCore
DocumentationNext.js recipe

Next.js recipe

Server Actions and Route Handlers — keep API keys off the client.

In Next.js App Router, call MailingCore from server-only code. Never put mc_live_ keys in client bundles.

Server Action

// app/actions/send-email.ts
'use server'

import { MailingCore } from 'mailingcore-js'

MailingCore.init({ apiKey: process.env.MAILINGCORE_API_KEY! })

export async function sendWelcomeEmail(email: string, name: string) {
  return MailingCore.send({
    to: email,
    subject: 'Welcome!',
    htmlBody: `<h1>Hello, ${name}!</h1>`,
    idempotencyKey: `welcome-${email}`,
  })
}

// app/contact/page.tsx
'use client'

import { sendWelcomeEmail } from '@/app/actions/send-email'

export function ContactForm() {
  async function handleSubmit(formData: FormData) {
    const email = formData.get('email') as string
    const name = formData.get('name') as string
    await sendWelcomeEmail(email, name)
  }

  return (
    <form action={handleSubmit}>
      <input name="name" required />
      <input name="email" type="email" required />
      <button type="submit">Send</button>
    </form>
  )
}

Route Handler (alternative)

// app/api/notify/route.ts
import { NextResponse } from 'next/server'
import { MailingCore } from 'mailingcore-js'

MailingCore.init({ apiKey: process.env.MAILINGCORE_API_KEY! })

export async function POST(req: Request) {
  const { email, subject, htmlBody } = await req.json()

  const result = await MailingCore.send({ to: email, subject, htmlBody })
  return NextResponse.json(result)
}

Environment variables

# .env.local (server only — no NEXT_PUBLIC_ prefix)
MAILINGCORE_API_KEY=mc_live_xxxx

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