Email Service Setup Guide: SendGrid & Mailgun Integration from Start to Expert

Email Service Setup Guide: SendGrid & Mailgun Integration from Start to Expert

Reliable email delivery is essential infrastructure for any website — from registration confirmations to marketing campaigns. This guide covers configuration of two most popular email services: SendGrid and Mailgun.

Why Use a Professional Email Service?

Sending email from your own server has drawbacks:

• Low IP reputation, often marked as spam
• Strict delivery limits from Gmail/Outlook
• Complex Postfix/Dovecot maintenance

Professional services provide:

• High-reputation sending IP pools
• Complete SPF/DKIM/DMARC authentication
• Real-time delivery analytics
• Elastic scalability

1. SendGrid Setup

Registration & API Key

1. Visit SendGrid and register
2. Free tier: 100 emails/day (permanent, ideal for small sites)
3. Settings → API Keys → Create API Key (Full Access)

SMTP Config

SENDGRID_API_KEY=SG.xxxxxxxxxxxxxxxxxxxx
[email protected]
SENDGRID_FROM_NAME=Your Site Name

const sgMail = require('@sendgrid/mail');
sgMail.setApiKey(process.env.SENDGRID_API_KEY);

const msg = {
  to: '[email protected]',
  from: { email: process.env.SENDGRID_FROM_EMAIL, name: process.env.SENDGRID_FROM_NAME },
  subject: 'Welcome!',
  text: 'Thank you for registering...',
  html: '<p>Thank you for registering...</p>',
};
sgMail.send(msg);

Domain Authentication

Add the following DNS records in SendGrid Dashboard → Settings → Sender Authentication:

# SPF
v=spf1 include:sendgrid.net ~all

# DKIM - CNAME records provided by SendGrid
# Domain verification - CNAME record

2. Mailgun Setup

Registration

1. Visit Mailgun and register
2. Free tier: first 3 months 5000/month, then 1000/month
3. Add your sending domain in Domains page

API Sending

import requests

def send_email(to, subject, html):
    return requests.post(
        f"https://api.mailgun.net/v3/{YOUR_DOMAIN}/messages",
        auth=("api", MAILGUN_API_KEY),
        data={
            "from": f"Your Site <noreply@{YOUR_DOMAIN}>",
            "to": [to],
            "subject": subject,
            "html": html
        })

DNS Records

TXT  @  v=spf1 include:mailgun.org ~all
TXT  xxxxx._domainkey  k=rsa; p=MIGfMA0GCSqGSIb3...
MX   mxa.mailgun.org  10
MX   mxb.mailgun.org  10

3. SPF, DKIM, DMARC Setup

SPF

Declares authorized sending servers:

v=spf1 include:sendgrid.net include:mailgun.org ~all

DKIM

Digital signature to verify email integrity:

[selector]._domainkey.[domain]  TXT  "v=DKIM1; k=rsa; p=[public_key]"

DMARC

Policy for unauthenticated emails:

_dmarc.[domain]  TXT  "v=DMARC1; p=quarantine; rua=mailto:[email protected]"

DMARC policies: p=none (monitor) → p=quarantine (spam) → p=reject (reject)

4. SendGrid vs Mailgun

5. Troubleshooting

16IDC Takeaway

For most small to medium websites, start with SendGrid's free tier (100 emails/day covers early needs). When delivery requirements grow, consider Mailgun. Configure SPF, DKIM and DMARC before going live — this is the single most important step for email deliverability.