Claude Code Email Testing: Check Emails Before Users Do

Your emails are built. Before real people start signing up, you want to know each one arrives, says the right thing and looks right. This guide covers Claude Code email testing in plain English: sending test emails to yourself, checking the details that most often go wrong, and a checklist to run before launch.

It's for anyone building a SaaS, site or tool in Claude Code who's about to go live. Every step is a message to Claude Code or something you check in your inbox. You won't write any code.

Why does Claude Code email testing matter?

Transactional emails are the automatic emails your project sends when someone does something, like signing up or resetting a password. They're often the first thing a new user gets from you. A broken link in a password reset email locks someone out. A welcome email that opens with "Hi ," and no name looks careless.

Claude Code writes and builds these emails with care, but it can't see your inbox. It doesn't know how an email looks on your phone, whether a link points to the right page on your live site, or whether an email fires at the right moment. Testing closes that gap.

Testing happens in two stages:

You need both.

How do you send test emails to yourself?

Ask Claude Code to send each email to an address you own. With SimpleSends connected, Claude Code can send test emails while you build. It does this through a connector: an MCP server, which is a standard way for Claude Code to use another service's tools.

Please send me a test of every transactional email we've built so far, to hello@yourcompany.com. Fill them with realistic sample details, like a first name and an order number, and start each subject line with "TEST" and the email's name so I can tell them apart.

What to expect: one email of each type lands in your inbox, labeled, so you can review them side by side. If one doesn't arrive, Claude Code can check the send log in SimpleSends and tell you whether it went out.

A few habits help:

• Send to inboxes you own. Made-up addresses don't reach anyone and show up as failed sends. Never send tests to real users.
• Use a fresh address for each new test user. If you use Gmail, you can add a plus sign and any word after your username, before the @, and Gmail still delivers it to you. That lets you sign up to your own SaaS several times as a "new" user.
• Test the awkward cases. Ask for one version with a very long name and one with no name at all.

What should you check in each test email?

Open every test and read it the way a new user would. Most problems fall into three groups: links, names and layout.

When something's wrong, describe what you saw:

In the welcome email test, the "Get started" button takes me to a page that says it can't be found. It should go to the dashboard on the live site. Please fix it and send me a new test.

Claude Code makes the change and sends a fresh copy. Repeat until every email passes. The same approach works after launch, whenever you want to update one of your emails.

How do your emails look on mobile and in different inboxes?

Check each email on your phone and on a computer, and in more than one email program if you can. Many people read email on their phone first, and each email program displays emails in its own way.

Three things often differ:

• Width. On a phone, text should be readable without zooming, and buttons should be big enough to tap.
• Images. Some email programs hold back pictures until the reader allows them. Classic Outlook, for example, blocks automatic picture downloads by default. Each email should still make sense with its images missing.
• Dark mode. Many people read email on a dark background. Check that your logo and text stay visible.

When something looks off, tell Claude Code which email program you used and what you saw. For more on building emails that hold up everywhere, see our guide to HTML emails in Claude Code.

The receipt email looks good on my laptop, but on my phone the order table runs off the right-hand side of the screen. Please make it fit narrow screens and send me another test.

How do you test emails the way your users will get them?

Once the test sends look right, use your live site the way a user would. When a real person signs up, your live project sends the email directly. Claude Code isn't involved at that point, so this is how you check every step works.

1. Sign up on your live site with a test address you own.
2. Do each action that should send an email: confirm your address, reset your password, start a trial, and make a test purchase if you sell something.
3. Note how long each email takes, and whether any never arrive.
4. Ask Claude Code about anything that's missing or slow.

I signed up on the live site with a test address about ten minutes ago and haven't had the welcome email. Can you check the send log in SimpleSends and tell me whether it went out?

Claude Code reads the delivery status and tells you whether the email was sent, delivered or failed. If it never went out, it can look into why and fix it. Our guide to checking whether an email was sent covers this in more detail.

When you're finished, ask Claude Code to remove your test accounts or mark them clearly, so they don't count toward your real sign-ups.

Your pre-launch email checklist

Run through this before you launch, and again whenever you add a new email. If you're not sure which emails your SaaS should send, start with our list of transactional emails every SaaS needs.

Download this checklist as a printable PDF.

For the rest of going live, see our SaaS launch checklist.