Email & SMS test automation for engineering teams
Mailosaur gives teams an isolated way to test message‑driven workflows without building and maintaining testing infrastructure.
Trusted by engineering teams building at scale
Focus on building features, not test infrastructure
Mailosaur lets engineering teams get on with development, rather than maintaining custom testing tools
Developer sandboxes
Allow developers to send, capture and analyze emails during development, with their own personal email and SMS sandbox.
Test email and SMS in one place
Use the same code to capture and test SMS messages, with a single platform that handles all communication testing consistently.
Environment segregation
Shield your development and staging environments by configuring them to send everything to Mailosaur.
Unlimited email addresses
Use any email address you want, no code required
Use a unique email address for every test, build, team member, environment, or any other use case you have. With Mailosaur supporting an unlimited number of email addresses you can use from anywhere.
Endorsed by engineers
5.0
Pretty easy to setup and use. Support is readily available. When there was an issue is recovered, Mailosaur team was able to rollout the fix in 2 days. That’s amazing.
5.0
Powerful tool for Automated testing of Emails and SMS. Very positive, if I were to change company and they didn't have a Mailosaur license I would push to get one.
5.0
It is fast, reliable, easy to setup and use. The rollout at both companies I used it, Extend and Siemens, was successful, and easily adopted by all.
Prevent flaky tests caused by shared state
Mailosaur gives you email addresses and dedicated phone numbers that can be used across tests, environments, builds, and team members.
Each test can operate in complete isolation, eliminating race conditions, inbox collisions, and timing‑related failures, resulting in predictable test behaviour you can trust in CI and locally.
Enforce strict environment isolation
Development, staging, and test environments can be configured to send everything to Mailosaur, ensuring no test emails reach real customers, no cross‑environment contamination occurs, and you can employ production‑like workflows without production risk
Works naturally inside your test stack
Mailosaur is designed to fit directly into real engineering workflows, whether you’re running tests locally or at scale in CI. You can:
Trigger real email and SMS sends from your application
Fetch messages programmatically
Assert on content, links, codes, and timing
Validate full end‑to‑end flows
Catch timing and delivery‑related failures early
Email and SMS issues don’t just come from missing content, they’re often caused by delays, retries, or unexpected ordering.
Mailosaur lets engineers inspect when messages arrive, correlate them with actions, and validate that systems behave correctly under real‑world timing conditions, surfacing issues that mock conditions can't.
Our products
Everything you need to test customer communication.
Email testing
Create end-to-end tests that rely on email. Test account verification emails, 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.
Test user interactions today
Test end-to-end scenarios, validate emails, and integrate with our API for seamless workflows.
Start your 14 day free trial today.