Claude Code Transactional Emails: Plan, Design and Send

Claude Code has told you your SaaS needs transactional emails, and you'd like to see the whole picture before you start. This guide covers Claude Code transactional emails from start to finish: deciding which ones you need, getting them written and designed, switching them on, and changing them months after launch.

You'll see the five stages every email goes through, and at each stage what you do (usually one short message) and what Claude Code does. A running example follows one SaaS all the way through.

No coding needed. You brief Claude Code the way you'd brief a designer or developer, and you approve what it shows you.

What are transactional emails?

Transactional emails are the automatic messages your project sends to one person because of something they did, or something that changed on their account. A "confirm your email" message, a password reset link and a payment receipt are all transactional emails.

In the US, the FTC draws the line in its CAN-SPAM guidance. An email counts as transactional or relationship when its main purpose is something like confirming a purchase the person already agreed to, sharing security information, or telling them about a change to their account or subscription. An email whose main purpose is promoting a product is a marketing email, and stricter rules apply.

This guide is about the first column. If you're not sure which kind you need, read transactional vs marketing emails. For the full list, with an example of each, see 12 transactional emails every SaaS needs.

How Claude Code transactional emails work, from plan to send

Every transactional email goes through the same five stages, and Claude Code can do the work at each one. Your job is to brief it and approve what it shows you.

1. Plan: Claude Code works out which emails your SaaS needs.
2. Design and write: it drafts each email, and you approve it.
3. Build: it connects each email to the right moment in your project.
4. Send: your live project sends each email automatically.
5. Test, fix and change: you ask, and Claude Code checks or updates things.

Here's the running example. Say your SaaS helps freelancers send invoices and get paid. People sign up, get a 14-day free trial, then pay monthly through Stripe. They can invite a colleague to their account. Your emails come from hello@yourcompany.com. We'll take this SaaS through every stage.

What do you need before Claude Code can handle your emails?

You need a transactional email service connected to Claude Code. Your project's code can decide when an email should go out, but it can't deliver one by itself. A transactional email service delivers your emails from your own domain.

Setting one up looks much the same with any service: an account, a verified domain, a secret key that your live project uses, and a small piece of sending code in your project. Most services are built for developers, so their dashboards and docs assume you know your way around all of that.

SimpleSends is built for people who build with Claude Code but don't write code. After one sign-up, everything happens in the chat. You connect it to Claude Code as a connector: a link that lets Claude Code work with another service. Connectors use MCP, short for Model Context Protocol, an open standard that its creators compare to a USB-C port for AI tools.

Here's how to connect it:

1. Sign up and set up your email address. Create your account on the SimpleSends website and follow the steps to set up the address you'll send from. To send from your own domain, this includes adding a few DNS records where your domain is registered. DNS records are settings that tell the internet how your domain works. Sign-up happens on the website, not in the Claude Code chat.

2. Add SimpleSends as a connector. In Claude Code, open Customize, then Connectors. Choose Add, then Add custom connector, and fill in:

   Field	What to enter
   Name	SimpleSends
   MCP server URL	https://mcp.simplesends.com/mcp

3. Log in to SimpleSends when Claude prompts you to connect.

4. Tell Claude Code it's connected. Back in the chat, send this message. Claude Code takes it from there, including adding what your project needs to send email.

   I've connected SimpleSends for all transactional email.

For a slower walkthrough, including your first test email, see how to send emails from Claude Code.

Plan: which emails does your SaaS need?

Ask Claude Code to look through your project and propose a list. It can see what your SaaS does, such as sign-ups, trials, payments and teams, and suggest an email for each moment that needs one. Ask it to hold off building until you've reviewed the list.

Look through my project and list every transactional email it should send. For each one, tell me who gets it, what triggers it and what it should say. Don't build anything yet. I'd like to review the list first.

What to expect: a list you can read in a minute or two. For the invoicing SaaS, it might look like this:

Other projects need other emails. A booking tool sends booking confirmations and reminders. A pre-launch site sends waitlist confirmations. Most sites have a contact form that should email you each message, and other forms can email you every entry too. Some founders also add a short series of onboarding emails in the first week.

Review the list the way you'd review a proposal. Cross out what you don't need yet, add anything missing, and change the timing if it feels wrong. Then tell Claude Code which emails to go ahead with. Our guide to planning which emails your SaaS needs goes into more detail.

Design and write: how does Claude Code draft each email?

Claude Code designs a look for your emails, writes the wording for each one, and shows you a preview before anything goes live. Start with the design, so every email matches.

Design one simple email layout for all my emails. Use the logo and colors from my site, keep it clean and easy to read on a phone, and make sure it still looks right in dark mode. Show me a preview.

Then move on to the wording. Give Claude Code your tone of voice once, and it uses it for every email.

Now write the welcome email in that layout. Our tone is friendly and plain, like a helpful colleague. Use the person's first name, keep it under 100 words, and add one button that opens their dashboard. Show me a preview and send a test to me.

What to expect: a preview in the chat, and a test email in your inbox. For the invoicing SaaS, the first draft might read like this:

From:hello@yourcompany.comSubject: Welcome aboard, Maya

Hi Maya,

Your account is ready. You can send your first invoice in about two minutes: add a client, add what you did, and press send.

Your free trial runs for 14 days, and you won't be charged unless you choose a plan.

Go to your dashboard

Any questions? Reply to this email and a real person will answer.

If something's off, say so the way you'd tell a copywriter: "Shorter, and less excited." "Mention that they can invite a colleague." Claude Code changes the draft and shows you again. Once you're happy, give it the go-ahead.

For more on each part, see our guides to designing email templates with Claude Code and briefing Claude Code like a copywriter. If you'd like ideas first, browse welcome email examples and password reset templates.

Build: how does each email get connected to the right moment?

Once you approve an email, Claude Code connects it to the moment it should go out. Every transactional email is set off by one of three kinds of moment.

You don't need to set up any of these yourself. Tell Claude Code when each email should go out, in plain words, and it builds the trigger.

Switch on the welcome email so it goes out as soon as someone confirms their email address. Set up the receipt so it goes out whenever Stripe confirms a payment. And set the trial-ending email to go out three days before a trial ends, at 9am New York time.

A tip on timing: scheduled jobs often run on UTC, the world's reference time, rather than your local time. Vercel's scheduled jobs, for example, always use UTC. Saying "9am New York time" means Claude Code can work out the right setting for you.

This is also the stage where your project gets what it needs to send email on its own. That's a small piece of sending code, plus a secret key that lets your live project use SimpleSends. The key is an API key, and it belongs in your project's private settings or your hosting settings, never in the code itself.

For a typical timing plan, see when to send each transactional email.

Send: what happens when a real customer triggers an email?

Your live project sends the email by itself, through SimpleSends, straight away. Claude Code doesn't need to be open, and nothing goes through the chat.

That's because the connector is for building. While you work in Claude Code, it lets Claude Code set up your emails, send you tests and check how sending is going. Once your SaaS is live, it sends real emails through SimpleSends directly, using the secret key and sending code in your project.

Back to the invoicing SaaS. At 3am, a freelancer clicks "forgot password". Your project creates a reset link, sends it through SimpleSends, and the email is on its way within moments. You're asleep, and so is the chat. The next morning, Stripe confirms her monthly payment, and the receipt goes out the same way.

Test, fix and change: how do you keep emails working?

You keep your emails working the same way you built them: by asking. Claude Code can send tests, look into problems and make changes, all from the chat.

Test before you launch. Get a test of every email in your inbox, with realistic details filled in, and check each one on your phone.

Before I launch, send me a test of every email on our list, with realistic sample details filled in. Then give me a list of what you sent so I can check each one off.

Our email testing guide includes a pre-launch checklist.

Fix problems by asking. If a user says an email never arrived, ask Claude Code to look. It can check the send logs in SimpleSends and tell you whether the email went out, and if it didn't, help work out why.

A user says they never got their password reset email this morning. Can you check in SimpleSends whether it went to [their email address] and tell me what happened?

When something does go missing, how to check whether your emails sent walks through the usual causes.

Change things later. Wording, design and timing can all change with one message. Ask for a preview, so nothing changes for your users until you've seen it.

Change the trial-ending email to go out five days before the trial ends instead of three, and make the button say "Choose a plan". Show me the new version and send me a test before it goes live.

Our guide to updating your emails by asking Claude Code covers previews and rolling a change back.

Can Claude Code set up all your transactional emails at once?

Yes. Once SimpleSends is connected, one message can start the whole process. Claude Code still stops at each stage for your approval, so you stay in charge of what your users receive.

Please set up every transactional email my SaaS needs. Start by showing me the list for approval. Then design one layout for all of them, write each email and show me a preview, and send me a test of each one before you switch anything on.

What to expect: the plan first, then a design, then each email in turn, with tests in your inbox along the way. You can also work through one email at a time, starting with the ones your SaaS can't run without: confirming an email address, password resets and receipts.