How to Migrate from SendGrid to SMTPfast

Why Migrate?

SendGrid is a powerful platform, but many developers only use a fraction of it. If your use case is sending password resets, order confirmations, and notifications, SMTPfast gets the job done with less complexity.

Step 1: Create Your SMTPfast Account

Sign up at smtpfa.st and verify your email address. No credit card required for the free tier (3,000 emails/month).

Step 2: Add Your Sending Domain

In the SMTPfast dashboard, go to Domains and add your sending domain. You will get:

• 3 CNAME records for DKIM
• An SPF include directive
• A recommended DMARC record

Add these DNS records alongside your existing SendGrid records. Both can coexist during the migration.

# Your SPF record can include both during migration
v=spf1 include:sendgrid.net include:amazonses.com ~all

Step 3: Generate an API Key

Go to API Keys in the dashboard and create a new key with email:send scope. Copy it immediately - you will only see it once.

Store it as an environment variable:

export SMTPFAST_API_KEY=sf_live_your_new_key

Step 4: Update Your Code

Here is how the code changes for each language.

Node.js

Before (SendGrid):

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

await sgMail.send({
  to: "[email protected]",
  from: "[email protected]",
  subject: "Your order has shipped",
  html: "<h1>Order shipped!</h1><p>Tracking: XYZ123</p>",
});

After (SMTPfast):

await fetch("https://smtpfa.st/api/v1/emails", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.SMTPFAST_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    from: "[email protected]",
    to: "[email protected]",
    subject: "Your order has shipped",
    html: "<h1>Order shipped!</h1><p>Tracking: XYZ123</p>",
  }),
});

You can remove the @sendgrid/mail dependency entirely. No SDK needed.

Python

Before (SendGrid):

from sendgrid import SendGridAPIClient
from sendgrid.helpers.mail import Mail

message = Mail(
    from_email="[email protected]",
    to_emails="[email protected]",
    subject="Your order has shipped",
    html_content="<h1>Order shipped!</h1><p>Tracking: XYZ123</p>",
)

sg = SendGridAPIClient(os.environ.get("SENDGRID_API_KEY"))
response = sg.send(message)

After (SMTPfast):

import requests
import os

response = requests.post(
    "https://smtpfa.st/api/v1/emails",
    headers={
        "Authorization": f"Bearer {os.environ['SMTPFAST_API_KEY']}",
        "Content-Type": "application/json",
    },
    json={
        "from": "[email protected]",
        "to": "[email protected]",
        "subject": "Your order has shipped",
        "html": "<h1>Order shipped!</h1><p>Tracking: XYZ123</p>",
    },
)

You can remove the sendgrid package. The requests library handles everything.

cURL

Before (SendGrid):

curl -X POST https://api.sendgrid.com/v3/mail/send \
  -H "Authorization: Bearer $SENDGRID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "personalizations": [{"to": [{"email": "[email protected]"}]}],
    "from": {"email": "[email protected]"},
    "subject": "Your order has shipped",
    "content": [{"type": "text/html", "value": "<h1>Order shipped!</h1>"}]
  }'

After (SMTPfast):

curl -X POST https://smtpfa.st/api/v1/emails \
  -H "Authorization: Bearer $SMTPFAST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "[email protected]",
    "to": "[email protected]",
    "subject": "Your order has shipped",
    "html": "<h1>Order shipped!</h1>"
  }'

Notice how much simpler the payload is. No nested personalizations array, no content array with type fields. Just from, to, subject, and html.

Step 5: Map SendGrid Concepts to SMTPfast

Step 6: Update Webhooks

If you use SendGrid's Event Webhook, you will need to set up equivalent webhooks in SMTPfast.

SendGrid event types mapped to SMTPfast:

Update your webhook handler to accept SMTPfast's payload format:

// Before: SendGrid webhook
app.post("/webhooks/sendgrid", (req, res) => {
  // SendGrid sends an array of events
  const events = req.body;
  events.forEach((event) => {
    switch (event.event) {
      case "delivered": // ...
      case "bounce": // ...
    }
  });
  res.sendStatus(200);
});

// After: SMTPfast webhook
app.post("/webhooks/email", (req, res) => {
  // SMTPfast sends one event per request
  const event = req.body;
  switch (event.type) {
    case "delivered": // ...
    case "bounced": // ...
  }
  res.sendStatus(200);
});

Step 7: Test in Parallel

Before cutting over completely, run both providers in parallel for a few days:

async function sendEmail(to, subject, html) {
  // Send via SMTPfast
  const smtpfastResult = await fetch("https://smtpfa.st/api/v1/emails", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.SMTPFAST_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ from: "[email protected]", to, subject, html }),
  });

  if (!smtpfastResult.ok) {
    // Fall back to SendGrid during migration
    console.error("SMTPfast failed, falling back to SendGrid");
    await sgMail.send({ to, from: "[email protected]", subject, html });
  }
}

Once you are confident SMTPfast is delivering reliably, remove the SendGrid fallback.

Step 8: Clean Up

After the migration is complete:

1. Remove the SendGrid SDK from your dependencies
2. Delete the SENDGRID_API_KEY environment variable
3. Remove SendGrid's SPF include from your DNS
4. Revoke your SendGrid API keys
5. Cancel your SendGrid plan

Migration Checklist

• SMTPfast account created
• Sending domain added and verified
• DNS records configured (DKIM, SPF, DMARC)
• API key generated and stored securely
• Code updated to use SMTPfast API
• Webhooks reconfigured
• Parallel testing completed
• SendGrid fallback removed
• SendGrid dependencies removed
• SendGrid API keys revoked
• SendGrid SPF include removed from DNS