Preview, test and trust every customer touchpoint
Test email and SMS end to end, with real-device previews built in. Validate critical user flows like sign-ups and authentication using secure inboxes, dedicated numbers, and accurate previews.
Email testing
Verify every message before it hits an inbox - check content, layout, links, and flows end-to-end.
SMS testing
Test OTPs, MFA codes, and transactional messages with dedicated numbers and secure delivery.
Email previews
See how your emails render across clients, devices and dark mode, with previews integrated into your email tests.
Trusted at scale, proven over time
1/3 billion
Emails tested by our customers
7 million
SMS messages tested
14 years
we've been helping customers
98.9%
Customer Satisfaction (CSAT) score
Built for your team
Mailosaur gives your team a dedicated, scalable environment for stress-free message testing and email previews your whole team can rely on.
No more dummy accounts or cluttered inboxes - create test addresses instantly, connect your CI/CD pipeline, and automate everything with flexible APIs and native integrations for Cypress, Selenium, and Playwright.
Book a demo to see how Mailosaur keeps your tests clean, fast, and reliable.
Preview every message before you hit send
Check how emails appear across email clients, devices, and even light and dark modes before they reach real inboxes.
Spot layout bugs, broken links, missing content, and formatting problems before they affect users.
Generate, review and share email previews from the same dashboard your team uses for email and SMS testing - no extra tools required.
Real devices are used to generate previews, not inaccurate emulations, leaving you with authentic results that reflect real user experience.
Works with any testing language and framework
Created for every team that touches communications
Reliably test email and SMS workflows like sign‑ups and password resets
Validate links, dynamic content, and one‑time codes/ magic links safely
Cover edge cases and negative scenarios with confidence
Combine manual checks with automation for full coverage
Preview emails across real inboxes, devices, and dark mode
Catch layout issues and broken links before campaigns go live
Share previews for fast feedback and sign‑off without forwarding emails
Hit send with confidence, knowing brand mistakes won’t reach customers
Test email and SMS in code with flexible APIs and framework support
Eliminate flaky tests caused by real inboxes or timing issues
Integrate message testing into CI/CD pipelines easily
Ship features knowing message‑driven flows won’t break
See how message‑driven journeys behave before customers rely on them
Catch issues that impact activation, trust, or conversion early
Align teams around one source of truth for message quality
Launch features confidently without email or SMS undermining UX
Build accessible, inclusive email journeys
Don’t settle for visual email inspections alone.
With Mailosaur you can validate accessibility of your emails against universally recognised standards, and ensure that your HTML isn’t impacting how your email renders across specific clients.
Reduce compliance risk and deliver clear, inclusive, and effective emails your team is proud of.
Customer stories
“If we couldn’t use Mailosaur anymore, it’d be a serious disruption. I’d only hope the replacement looks and works half as well.”
See Mailosaur in action
See Mailosaur in action with a free, personalised demo led by one of our experts, or jump straight in with a 14-day free trial to explore the dashboard, preview messages, and experience how easy it is to test email and SMS in your own flows.
// Step 1: Send an email into Mailosaur
// Step 2: Fetch your message via Mailosaur
const MailosaurClient = require('mailosaur');
const mailosaur = new MailosaurClient('YOUR_API_KEY');
const criteria = {
sentTo: 'anything@YOUR_SERVER_ID.mailosaur.net',
};
const email = await mailosaur.messages
.get(serverId, criteria);
// Step 3: Complete the process
expect(email.subject).toBe('My password reset');Automate tests in minutes
With just a few lines of code added to your project
Integrate Mailosaur with any testing framework - Cypress, Playwright, Selenium, and more. Set it up in minutes with just a few lines of code, no matter your framework or language of choice.
Automate flows you never thought you could, from MFA to password resets, and easily replicate real-world scenarios.
To start, make sure you have a Mailosaur plan. Then, just visit our documentation to get started.
// Step 1: Send an email into Mailosaur
// Step 2: Fetch your message via Mailosaur
const MailosaurClient = require('mailosaur');
const mailosaur = new MailosaurClient('YOUR_API_KEY');
const criteria = {
sentTo: 'anything@YOUR_SERVER_ID.mailosaur.net',
};
const email = await mailosaur.messages
.get(serverId, criteria);
// Step 3: Complete the process
expect(email.subject).toBe('My password reset');Why choose Mailosaur?
Manual and automated testing
Switch seamlessly between manual and automated testing, as you run end-to-end tests for critical flows. Simple setup, reliable results.
Test secure features
Stop skipping tests for secure areas of your product. Test features that are protected by two-step verification or MFA with Mailosaur.
End-to-end visibility
Inspect every detail of your messages, from subject lines to headers and links, in one intuitive dashboard.
Chosen by QA, Product, and Marketing teams alike
Hear from our customers about how Mailosaur became an integral part of their testing processes.
5.0
Powerful tool for automated testing of emails and SMS. If I were to change company and they didn't have a Mailosaur license I would push to get one.
5.0
We've absolutely loved using Mailosaur. Our automated testing is a breeze with Mailosaur and I use for manual QA as well.
4.5
The UI is really smooth and learning curve is minimal for this software. Even a beginner can get hold of their easy to use process and adapt very quickly.
Security standards you can trust
We get it - starting any subscription comes with fresh concerns around security.
Mailosaur is ISO 27001:2022 certified, GDPR compliant, and built with strict data controls - so every test message stays private and protected.
Frequently asked questions
Test anything your users might do
Automate end-to-end scenarios, validate emails, and integrate with our API for seamless workflows.
Start your 14 day free trial today.