EMAIL / LESSON 05

SendGrid Basics.

What Twilio SendGrid is, how it differs from Resend, and when it is the right pick

Written by Andrew Lee JenkinsPublished Oct 5, 20269 min readFree lesson

You just met Resend, a small and focused tool for sending email from your app. Now say hi to its MUCH bigger cousin. Twilio SendGrid is one of the oldest and largest email platforms out there, and you're gonna bump into it on a lot of real projects.

What Is SendGrid?

SendGrid is an email service owned by Twilio, the company known for text messaging and phone APIs. Its documentation sums it up in one line. You use it to "build transactional and marketing email solutions."

That one sentence holds the two big ideas of this whole lesson, so let's unpack it.

Transactional email is mail your app sends because somebody did something, like a password reset, a receipt or a shipping alert. One person gets one email, triggered by something they did.
Marketing email is mail you send to a group on purpose, like a newsletter, a product announcement or a sale. Lots of people get the same message, and it goes out when YOU decide.

Resend is built mostly around the first kind. SendGrid was built to handle both from a single account.

The Two Halves of SendGrid

SendGrid is really two products hiding under one login.

Step 1. The Email API

This is the half developers use. Twilio describes it as a way to "create, send, and manage emails at scale through RESTful APIs or SMTP relay."

Those two terms are just two doors into the same building.

The Web API is the modern way. Your code calls SendGrid over the internet, pretty much like any other API you've seen. There are official libraries for popular languages, including Node.js.
SMTP relay is the older, works-with-everything way. SMTP is the standard language email servers have been speaking for decades. Almost any tool that can send email, from a WordPress plugin to some crusty old server script, can be pointed at SendGrid's SMTP server with a username and password.

Having both comes in handy. Writing fresh code? You'll use the Web API. Plugging in an existing tool that only knows SMTP? It can still send through SendGrid.

Step 2. Marketing Campaigns

This is the half a marketer uses, usually without writing a single line of code. It lives in the SendGrid dashboard and comes with these tools.

A design editor for building emails that look good on phones and computers
Contact lists and segments, so you can send a message to just the people it fits
Automations, which send emails on their own when something happens
Sign-up forms that drop new subscribers straight onto a list
Email testing, with inbox previews and spam checks before you hit send

Twilio's own product page puts it like this. The Email API handles "receipts, password resets, and shipping alerts right next to your marketing campaigns." So one platform covers both jobs.

How SendGrid Compares to Resend

Neither one wins at everything. They're built for different people.

	Resend	SendGrid
Main focus	Developer email from code	Developer email and marketing email
Ways to send	API and SDKs	Web API, SMTP relay, and a dashboard for campaigns
Feel	Small, modern, minimal	Large platform with many settings
Best fit	A new app that just needs to send email	A business that also runs newsletters and campaigns, or an existing tool that speaks SMTP

The trade-off is pretty simple. Resend gets you sending with very little to learn. SendGrid has more to learn up front, but it covers a lot more ground once you're set up.

When Should You Pick SendGrid?

SendGrid is a strong pick when any of these sound like you.

You need marketing email too. If the same business sends receipts from the app AND a monthly newsletter, SendGrid can handle both from one place.
A non-developer will send campaigns. Marketing Campaigns gives them an editor and contact lists without ever touching code.
You're hooking up an older tool. Tons of plugins, CRMs and servers only speak SMTP. SendGrid's SMTP relay works with them.
Your client already uses it. Lots of businesses have had a SendGrid account for years. Using what they've already got often beats dragging them somewhere new.

Resend might be the better fit when you're building a brand new app, you only need app emails and you want the shortest path from zero to sent.

What Does It Cost?

SendGrid offers a free trial, and the official pricing page says you don't need a credit card to start. As of October 2026 the trial lasts 60 days and lets you send up to 100 emails a day. There's no free plan waiting after it, so once it ends you move to a paid plan to keep sending. The Email API and Marketing Campaigns each have their own plans.

Prices and trial limits change, so always check the current numbers on the Email API pricing page and the Marketing Campaigns pricing page before you promise anything to a client.

The Same Rules Still Apply

Everything you learned about why email is hard is still true here. Picking a bigger platform doesn't make spam filters, authentication or sender reputation go away.

SendGrid helps with all of it, but you still have to prove you own the address you're sending from. In the next lesson you'll set that up properly, along with your API key and your very first send.

TL;DR

Twilio SendGrid is a large email platform that handles both transactional and marketing email
The Email API lets your code send through a Web API or through SMTP relay
Marketing Campaigns gives non-developers an editor, contact lists, automations and sign-up forms
Resend is smaller and focused on developers, while SendGrid covers more ground with more to learn
Pick SendGrid when you need marketing email too, when a tool only speaks SMTP or when a client already uses it
There's a free trial, but check the official pricing pages for current limits and plans

What's Next?

In the next lesson you'll create a SendGrid account, make an API key, verify your sender and send your first email from Node.js...

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