How to Integrate Replit with Mailgun

1# Python — verify Mailgun secrets are loaded
2import os
3
4required_secrets = ["MAILGUN_API_KEY", "MAILGUN_DOMAIN"]
5for secret in required_secrets:
6    value = os.environ.get(secret)
7    if not value:
8        raise EnvironmentError(f"{secret} not found in Replit Secrets. Add it via the lock icon in the sidebar.")
9    print(f"{secret}: loaded ({len(value)} chars)")
10
11print("All Mailgun secrets verified.")

1// Node.js — Send email via Mailgun REST API (mailgun.js)
2const MAILGUN_API_KEY = process.env.MAILGUN_API_KEY;
3const MAILGUN_DOMAIN = process.env.MAILGUN_DOMAIN;
4const MAILGUN_BASE_URL = process.env.MAILGUN_BASE_URL || 'https://api.mailgun.net/v3';
5
6async function sendEmail({ to, subject, text, html, from }) {
7  const sender = from || `noreply@${MAILGUN_DOMAIN}`;
8
9  const formData = new URLSearchParams();
10  formData.append('from', sender);
11  formData.append('to', to);
12  formData.append('subject', subject);
13  if (text) formData.append('text', text);
14  if (html) formData.append('html', html);
15
16  const credentials = Buffer.from(`api:${MAILGUN_API_KEY}`).toString('base64');
17
18  const response = await fetch(`${MAILGUN_BASE_URL}/${MAILGUN_DOMAIN}/messages`, {
19    method: 'POST',
20    headers: {
21      'Authorization': `Basic ${credentials}`,
22      'Content-Type': 'application/x-www-form-urlencoded'
23    },
24    body: formData.toString()
25  });
26
27  if (!response.ok) {
28    const error = await response.text();
29    throw new Error(`Mailgun error ${response.status}: ${error}`);
30  }
31
32  return response.json();
33}
34
35module.exports = { sendEmail };

1// Node.js — Express email API server (server.js)
2const express = require('express');
3const { sendEmail } = require('./mailgun');
4const app = express();
5app.use(express.json());
6
7app.post('/send-email', async (req, res) => {
8  const { to, subject, text, html } = req.body;
9
10  if (!to || !subject || (!text && !html)) {
11    return res.status(400).json({
12      error: 'Required fields: to, subject, and text or html'
13    });
14  }
15
16  // Basic email validation
17  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
18  if (!emailRegex.test(to)) {
19    return res.status(400).json({ error: 'Invalid email address' });
20  }
21
22  try {
23    const result = await sendEmail({ to, subject, text, html });
24    console.log(`Email sent to ${to}, message ID: ${result.id}`);
25    res.json({ success: true, messageId: result.id, message: result.message });
26  } catch (err) {
27    console.error('Email send failed:', err.message);
28    res.status(500).json({ error: 'Failed to send email', details: err.message });
29  }
30});
31
32app.listen(3000, '0.0.0.0', () => console.log('Email server running on port 3000'));

1// Node.js — Mailgun webhook receiver (add to server.js)
2const crypto = require('crypto');
3
4const MAILGUN_WEBHOOK_KEY = process.env.MAILGUN_WEBHOOK_KEY;
5
6function verifyMailgunSignature(timestamp, token, signature) {
7  if (!MAILGUN_WEBHOOK_KEY) return true; // Skip in dev mode
8  const value = timestamp + token;
9  const hash = crypto
10    .createHmac('sha256', MAILGUN_WEBHOOK_KEY)
11    .update(value)
12    .digest('hex');
13  return hash === signature;
14}
15
16app.post('/mailgun-webhook', express.json(), (req, res) => {
17  const { signature, 'event-data': eventData } = req.body;
18
19  if (!verifyMailgunSignature(
20    signature.timestamp,
21    signature.token,
22    signature.signature
23  )) {
24    return res.status(401).json({ error: 'Invalid webhook signature' });
25  }
26
27  const { event, recipient, message } = eventData;
28  console.log(`Email event: ${event}, recipient: ${recipient}`);
29
30  // Handle specific events
31  switch (event) {
32    case 'delivered':
33      console.log(`Delivered to ${recipient}, message ID: ${message.headers['message-id']}`);
34      break;
35    case 'bounced':
36      console.log(`Bounced for ${recipient}: ${eventData['delivery-status']?.description}`);
37      break;
38    case 'complained':
39      console.log(`Spam complaint from ${recipient}`);
40      break;
41  }
42
43  res.json({ received: true });
44});

1# Python — Flask Mailgun integration (app.py)
2import os
3import requests
4from flask import Flask, request, jsonify
5
6app = Flask(__name__)
7
8MAILGUN_API_KEY = os.environ["MAILGUN_API_KEY"]
9MAILGUN_DOMAIN = os.environ["MAILGUN_DOMAIN"]
10MAILGUN_BASE_URL = os.environ.get("MAILGUN_BASE_URL", "https://api.mailgun.net/v3")
11
12def send_email(to, subject, text=None, html=None, sender=None):
13    if not sender:
14        sender = f"noreply@{MAILGUN_DOMAIN}"
15    payload = {
16        "from": sender,
17        "to": to,
18        "subject": subject
19    }
20    if text:
21        payload["text"] = text
22    if html:
23        payload["html"] = html
24
25    response = requests.post(
26        f"{MAILGUN_BASE_URL}/{MAILGUN_DOMAIN}/messages",
27        auth=("api", MAILGUN_API_KEY),
28        data=payload,
29        timeout=10
30    )
31    response.raise_for_status()
32    return response.json()
33
34@app.route("/send-email", methods=["POST"])
35def api_send_email():
36    data = request.get_json()
37    to = data.get("to")
38    subject = data.get("subject")
39    text = data.get("text")
40    html = data.get("html")
41
42    if not to or not subject or not (text or html):
43        return jsonify({"error": "Required: to, subject, and text or html"}), 400
44
45    try:
46        result = send_email(to=to, subject=subject, text=text, html=html)
47        return jsonify({"success": True, "messageId": result.get("id")})
48    except requests.exceptions.HTTPError as e:
49        return jsonify({"error": str(e)}), 500
50
51if __name__ == "__main__":
52    app.run(host="0.0.0.0", port=3000)