Multifactor authentication testing
Mailosaur provides a safe and reliable way to test one‑time passwords and authentication messages before they reach real users.
Trusted to test teams' most sensitive messages
Why OTP and MFA messages matter
One time passwords and authentication messages play a crucial role in how users access and trust your product, underpinning account sign up, login, and other sensitive actions.
If an email is delayed, SMS code never arrives, or verification message contains the wrong content, users can be locked out or abandon the journey altogether. These issues are often only discovered too late, after a release or if users report problems.
Support complete verification journeys
OTP and MFA messages are part of wider user journeys. Mailosaur helps teams test these journeys end‑to‑end by confirming:
Correct message triggered
The correct authentication message is triggered at the right point in the journey
Message is routed correctly
The message is sent to the intended email address or phone number
Arrives as intended
The message arrives promptly and within expected timeframes
Links and codes available
Codes or links are present, readable, and usable
Functional follow-on
The user can successfully proceed after using the code or link
Catch broken messages
Missing, delayed, or incorrect messages are easy to identify before users are impacted
Consistent testing across environments
OTP and MFA issues can be difficult to track down and reproduce, making them difficult to replicate across environments.
Mailosaur allows teams to test messages consistently across development, QA, staging, and pre production environments, helping teams verify changes behave as expected before they reach users, and reducing reliance on manual spot checks that are easy to miss or forget.
Works with your existing authentication setup
Mailosaur does not require changes to how your application sends authentication messages. Your system continues to send real emails and SMS messages using your existing providers and logic, they're simply received in a controlled environment, making it easier to inspect, test, and validate authentication behaviour.
Reduce risk at critical points
Authentication messages sit at some of the most fragile points in the user journey. When they fail, users can’t proceed and teams often only hear about it through support channels.
By making OTP and MFA messages visible and testable earlier, teams can identify issues before they impact real users. This reduces release risk, improves reliability, and supports smoother login experiences, maintaining customer satisfaction.
Secure by design
Testing authentication messages shouldn’t introduce security risk.
This is why Mailosaur provides safe, isolated test email addresses and phone numbers (so there's no risk of exposing real user data), full control over environments and access (including the ability to set hierarchal permissions by inbox), and enterprise‑ready security features for sensitive workflows.
Our products
Everything you need to test customer communication
Email testing
Create end-to-end tests that rely on email. Test account verification flows, password resets, email tracking and more.
Email previews
Instantly see how your email will look to any recipient, no matter what email client they use, so there are no nasty surprises.
SMS testing
Build text messages that work. Create end-to-end tests that cover identity verification, alerting, promotional messages and more.
Ready to give it a go?
Start testing your authentication
You can start testing your most crucial flows for free by signing up to one of our 14-day free trials, or book a demo with one of our experts.