AI Email Template Generator: Design Emails With Claude Code

An AI email template generator turns a short description of your brand into finished, good-looking emails. If you build with Claude Code, you already have one: an AI email designer that works inside your project. Claude Code can design every transactional email your SaaS sends (the automatic emails people get when they sign up, reset a password or pay you) without you opening a template editor.

This guide covers what good transactional email design looks like, what to tell Claude Code, how to review its drafts, and how to use one design for every email.

What makes a good transactional email design?

A good transactional email is clear, quick to read and recognizably yours. People open it to do one thing, such as reset a password, so the design should point to that one action.

Two guidelines from the W3C, the group that sets web standards, make useful yardsticks. Normal text needs a contrast ratio of at least 4.5:1 against its background, and large text (18 point, or 14 point bold) at least 3:1. Buttons should be at least 24 by 24 pixels, and bigger is better for the main one. Ask Claude Code to check both for you.

Can Claude Code be your AI email template generator?

Yes. Many AI email template generators make a design you then copy into another tool. Claude Code works inside your project, so the design it makes is the one your product sends. You describe what you want, it builds a preview, and you give feedback until it's right.

With SimpleSends connected, Claude Code can also send test emails to your own inbox from the chat, so you can see the design on your phone before any customer does. The connection uses a connector: a link that lets Claude Code use another service while you build. It's built on MCP, an open standard for connecting AI tools to other services (what is MCP?).

Once your SaaS is live, real emails go out from your project through SimpleSends. The chat is where you design and test them.

How do you brief Claude Code on your brand?

Give Claude Code what you'd give a designer. The more specific the brief, the closer the first draft.

Then send a brief like this one:

I'd like one design for all of our transactional emails. Use the logo from our site header, our main blue (#1F4FD8) for buttons and links, and our site's font with a common fallback. Keep it clean and calm: white background, one column, plenty of space, and one clear button per email. Start with the welcome email and show me a preview before you build anything else.

Claude Code builds a preview of the welcome email and explains its choices. For more on what a full set of templates covers, see how to get Claude Code to write and design your email templates.

How do you review the draft and ask for changes?

Look at the preview the way a customer would: on a phone first, then on a computer. Then tell Claude Code what to change in plain words, the same way you'd give feedback to a designer.

Ask yourself: can you tell who sent it at a glance, is the main action obvious, and is anything hard to read or worth cutting? Here's what one round of feedback often changes:

This is close. Make the logo smaller, cut the intro to two sentences, and keep only the "Open your dashboard" button. The gray text is hard to read, so darken it until it meets the 4.5:1 contrast guideline. Then send a test to me at hello@yourcompany.com.

A few minutes later, the revised email lands in your inbox. It might read like this:

SubjectWelcome to YourCompany, Sam

Hi Sam,

Your account is ready. Here's how to get set up in a few minutes:

• Add your first project
• Invite a teammate
• Connect your calendar

Open your dashboard

Questions? Reply to this email or write to help@yourcompany.com.

YourCompany · You're getting this email because you created an account.

Design and wording are separate jobs, so once the look is settled, see how to get Claude Code to write your SaaS emails. For a full pre-launch check, see how to test your emails before your users see them.

How do you make emails work on mobile and in dark mode?

Ask for both in your brief, then check both in a test email.

On mobile, a single column, a readable text size and a full-width button do most of the work. Gmail supports styles that adjust to screen width, so the layout can change for phones.

Dark mode, the setting that switches a screen to light text on a dark background, is less predictable. Google's list of what Gmail can detect covers screen width, orientation and resolution, but not a dark-mode preference. Some inboxes also recolor emails on their own. So the safest design is one that holds up whether its colors stay as you set them or get flipped:

• a logo that stays visible on a dark background
• button text that stays readable whatever the button color
• no important words inside images
• color never used as the only signal

It also helps to include a plain-text version. An email can carry a plain and a designed version, and each inbox shows the richest one it can display.

Before we finalize, check the welcome email on a narrow phone screen and in dark mode. Make sure the logo still shows on a dark background, the button text stays readable, and there's a plain-text version too. Send me tests so I can check on my phone.

Email designs are built in HTML, the code that lays out web pages and emails. For the detail behind how that works across Gmail and Outlook, see how to get Claude Code to build HTML emails that look good everywhere.

How do you use one design for every email?

Once you approve the welcome email, ask Claude Code to turn its header, footer, colors and button style into one shared layout, then build every other email from it. A change to the shared layout then carries through to every email.

Use this design for every transactional email: welcome, email verification, password reset, receipts and trial reminders. Keep the header, footer and button style the same, and show me each one before it goes live.

Claude Code works through the list, showing you each one. To see the full journey, from planning which emails you need to sending them at the right moment, read transactional emails in Claude Code. When something needs changing later, see how to update your SaaS emails by asking Claude Code.

How do you get started with SimpleSends?

SimpleSends is a transactional email service built for people who build with Claude Code but don't write code. The sign-up, connect steps and help are written in plain English, without developer jargon.

1. Sign up on the SimpleSends website and follow the steps there to set up the email address you'll send from. To send from your own domain, this includes adding a few DNS records (short settings that tell the internet your domain allows SimpleSends to send for it) where your domain is registered.
2. In Claude Code, open Customize, then Connectors, choose Add, then Add custom connector. Enter the name SimpleSends and the server URL below, click Continue through the screens that follow, then Add.
3. When Claude prompts you to connect, log in to SimpleSends.
4. Back in the Claude Code chat, tell Claude Code: "I've connected SimpleSends for all transactional email." It takes it from there, including adding what your project needs to send email.