A Mailosaur alternative for email tests: catch-all inboxes

If you test sign up, password reset or magic link emails, Mailosaur is probably the tool you know. This page is about switching: the limits that send teams looking, when to stay, and how to port the tests. The feature table is on Mailbay vs Mailosaur, and the other switch guides are on the alternatives index.

Why people look for an alternative#

• A daily email limit that rejects mail. Personal is based on 500 emails a day, Core on 2,500 ^[1]. The limit counts received and sent mail together, and once it is hit “further emails are automatically rejected” until midnight UTC ^[2]. A busy CI day can fail tests for a reason that has nothing to do with your app.
• Seats and inboxes by plan. Personal includes 1 user (up to 3) and 1 inbox; multiple inboxes and 5 seats start on Core, from $50 a month billed annually ^[1].
• Retention set by the plan. The longest retention you can set depends on your plan ^[4].
• A ten second default wait. messages.get waits 10 seconds by default ^[5], and the waiting happens in the SDK; the API docs recommend the SDK's get over search because it waits for you ^[6]. Without one of their SDKs you write the polling yourself.

When to stay with Mailosaur#

• You test SMS too, or use its email previews and spam analysis. Mailbay has none of these.
• You want a maintained SDK for your framework. Mailosaur documents Playwright, Cypress, Selenium, Robot Framework, Postman and libraries for Node.js, Java, .NET and Python ^[7]. Mailbay has a REST API and a CLI, and a general Node SDK coming to npm, but no test framework plugins.
• Your QA team lives in its dashboard and its plans fit your volume. Mailosaur is a mature product; Mailbay is in private beta.

How Mailbay differs#

Mailbay is in private beta and free while it runs. The Mailbay prices below are the planned plans from our pricing page; billing is not live yet.

The Catch-all is the part teams notice first: every test makes up its own address, so there are no inboxes to create or clean up, and parallel workers never read each other's mail. The recording below is a real message sent over SMTP to an address that was never created.

Other options#

Mailpit and similar self hosted catchers are free and fast for mail your app sends inside CI, but they do not receive mail from the internet. MailSlurp and Mailinator are hosted testing services like Mailosaur. If a test needs to receive real mail from a third party, use a hosted service.

Moving tests from Mailosaur#

1. Make a Playground key. The Catch-all lives in the Playground project, so create the API key there.
2. Replace the address. Where tests build something@SERVER_ID.mailosaur.net, build something@CODE.mailbay.email with your workspace's code from GET /v1/me.
3. Replace the wait. Where tests call mailosaur.messages.get(serverId, { sentTo }), call Mailbay's wait with to set to the same address.
4. Read the code. Mailosaur returns codes in text.codes; Mailbay returns them in codes, and links in links.

// Mailosaur
const email = await mailosaur.messages.get(serverId, { sentTo: address });
const code = email.text.codes[0].value;

// Mailbay: one request that blocks until the mail arrives
const res = await fetch(`${API}/inboxes/${catchAllId}/wait?` +
  new URLSearchParams({ to: address, timeout: "30" }), { headers });
const { codes } = await res.json();
const code = codes[0];

The complete fixture, config and a passing run are on the Playwright integration page. The idea behind it is explained in catch-all inboxes for end to end tests.

How the catch-all fits a test suite, in three steps, is on Mailbay for QA and test engineers.