Send transactional email with SendGrid

• Pick SendGrid when — you're at enterprise volume (1M+ emails/month), need sub-accounts for multiple brands/teams, want both transactional + marketing in one tool, or need dedicated IPs.
• Pick Resend for dev-first DX at small/medium scale.
• Pick Postmark for best inbox placement at small/medium scale.
• Pick AWS SES for the cheapest per-email at any scale, if you're OK doing more setup yourself.

Sign up at signup.sendgrid.com ↗. The free tier is 100 emails/day forever after the 60-day trial; paid plans start at $19.95/mo for 50K emails.

SendGrid's signup process includes account verification — they sometimes ask follow-up questions for new accounts to fight abuse. Be patient.

Two options:

• Single Sender Verification — verify one email address. SendGrid emails a confirmation link. Easiest for getting started, but limits deliverability. Docs ↗.
• Domain Authentication — verify an entire domain via DNS. Recommended for production. Docs ↗.

For Domain Authentication: Settings → Sender Authentication → Authenticate Your Domain. Pick your DNS host; SendGrid generates 3 CNAME records:

• em1234.yourdomain.com → SendGrid's mail server
• s1._domainkey.yourdomain.com → DKIM record 1
• s2._domainkey.yourdomain.com → DKIM record 2

Add at your DNS provider; come back to SendGrid and click Verify. Usually green in 10–30 minutes.

Settings → API Keys → Create API Key. Pick:

• API Key Name — descriptive (e.g., "production-server").
• API Key Permissions — pick Restricted Access and grant only what your app needs. For just sending: Mail Send: Full. Avoid Full Access for production.

Copy the key (starts with SG.). Shown once. Store in env:

SENDGRID_API_KEY=SG.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

npm install @sendgrid/mail

Other languages: Python, Ruby, PHP, Java, C#, Go ↗.

import sgMail from "@sendgrid/mail";

sgMail.setApiKey(process.env.SENDGRID_API_KEY);

await sgMail.send({
  to: "[email protected]",
  from: "[email protected]",            // must be a verified sender
  subject: "Hello from SendGrid",
  text: "Plain text version",
  html: "<p>HTML body</p>",
});

Check your recipient. If it's not there, look at Activity in the SendGrid dashboard — every send is logged with its delivery status and the recipient mail server's response.

For repeatable emails (welcome, receipt, password reset), use Dynamic Templates — designed in the SendGrid dashboard, sent by ID.

Email API → Dynamic Templates → Create Template. Use the drag-and-drop editor or HTML editor. Variables look like {{name}} using Handlebars syntax.

Send by template ID:

await sgMail.send({
  to: user.email,
  from: "[email protected]",
  templateId: "d-xxxxxxxxxxxxxxxxxxxxxxxx",     // starts with d-
  dynamicTemplateData: {
    name: user.name,
    verifyUrl: `https://yourapp.com/verify/${token}`,
  },
});

Editing the template in the dashboard updates all future sends immediately — no deploy needed.

Settings → Mail Settings → Event Webhook. Add your endpoint URL. Pick events: delivered, opened, clicked, bounced, dropped, spam reported.

SendGrid POSTs your URL with batches of events. Enable signed event webhooks for security — SendGrid signs the payload with a key you verify on your end. Signed webhook docs ↗.

What to do with the events:

• Bounced — mark recipient as invalid; stop sending until you re-verify the address.
• Spam reported — same; this user actively flagged your mail as spam.
• Delivered / opened / clicked — feed into your analytics (e.g., PostHog) for engagement tracking.

Shared IPs are the default on free / starter plans. At higher volume you can request a dedicated IP — but a new IP has no sending reputation. You need to "warm it up" by gradually increasing volume over 4–6 weeks.

SendGrid automates this: enable IP warmup in account settings; SendGrid throttles your sends to safe daily limits that ramp up over time. Skip the warmup and you'll land in spam everywhere.

IP warmup schedule ↗. For volumes under ~100K/month, the shared IP pool is fine.

SendGrid's Subusers feature lets a single SendGrid account own multiple sub-accounts with their own API keys, sender authentication, and IP pools. Useful when you have multiple products or run a multi-tenant platform.

Settings → Subuser Management. Create a subuser with its own credentials; assign IP pools and limits. Subusers docs ↗.

Most indie/SaaS users don't need this. Pick a different provider if you're not at the scale that justifies a multi-account hierarchy.

• "The from address does not match a verified Sender Identity" — the sender wasn't verified, or you typed a different address than what you verified. Recheck Sender Authentication.
• "Account temporarily blocked" — SendGrid's anti-abuse system flagged something. Usually clears in a few hours; contact support if it persists.
• "Maximum credits exceeded" — you hit your plan's daily/monthly cap. Upgrade or wait.
• Emails delivered but going to spam — almost always missing DNS records. Check Sender Authentication status; make sure DMARC is set up too.

Free: 100 emails/day forever (after a 60-day 40K/month trial). Essentials: $19.95/mo for 50K emails. Pro: $89.95/mo for 100K + dedicated IP. SendGrid pricing ↗.

Per-email cost is competitive at scale ($0.0004 / email at the millions-per-month tier). For < 50K/month, Resend is cheaper for the same DX.