# InboxSpec vs Mailosaur

A dated comparison of price, daily limits, waiting and custom domains, including where Mailosaur is better.

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**Checked on 24 October 2026**

Every Mailosaur fact on this page comes from its public pricing page and documentation on that date, listed under [Sources](https://www.inboxspec.com/docs/markdown/compare-mailosaur.md#sources). Prices and plans change, so check their current pages before deciding. If something here is wrong or out of date, tell us at [hello@inboxspec.com](mailto:hello@inboxspec.com) and we will correct it.

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## At a glance

| Topic | Mailosaur | InboxSpec |
| --- | --- | --- |
| Price | Personal from $20/month and Core from $50/month, both shown billed annually. Enterprise is custom. A 14-day trial is offered on Personal. | Free $0 (500 messages/month), Starter $19 (10,000), Developer $49 (50,000), Team $129 (150,000). Monthly billing only. |
| Volume | Personal: from 15,000 inbound emails/month, based on a daily limit of 500. Core: from 75,000/month, based on a daily limit of 2,500. | A monthly allowance with no daily cap. Overage is optional on paid plans. |
| When the limit is reached | Further emails are rejected until the count resets at midnight UTC. A test waiting for that email sees a timeout. | A timeout is a normal result with status "timeout", a count of non-matching arrivals and a hint. A spent allowance is a separate quota\_exceeded error. |
| People | Personal includes 1 user and supports up to 3. Core includes 5 seats. | No per-seat fees on any plan. Every plan has the same fair-use ceiling of 1,000 people per workspace. No per-inbox, per-request or MCP charge. |
| Custom receiving domain | Enterprise plans only. | Shared domain on Free. Custom receiving domains on every paid plan: 1 on Starter, 3 on Developer, 10 on Team. |
| Waiting | The client libraries wait by repeating a search request. The REST API has no wait endpoint. The default timeout is 10 seconds, and by default only the last hour of mail is searched. | POST /v1/messages/wait blocks on the server for up to 285 seconds per call (default 120). Waiting is not metered and not rate limited; concurrent-wait limits apply. |
| Codes and links | Extracted codes and links on the full message, read after the wait. | The wait response already contains ranked codes and links classified as verify, sign\_in, reset\_password, unsubscribe or other. |
| Capture outgoing mail | SMTP into an inbox on every plan. POP3 and IMAP need Core or Enterprise. | Capture SMTP with STARTTLS on port 587 on every plan, including Free. |

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## Where Mailosaur is the better choice

-   It does more than receive email: email compatibility testing on every plan, accessibility testing on Core, and SMS testing and email previews as add-ons.
-   Official client libraries in many languages, plus test-framework helpers. InboxSpec offers REST examples in seven languages, but its own packages are not yet public.
-   Every address under an inbox's subdomain works without registering it first. InboxSpec requires you to register an inbox before mail is sent to it.
-   Enterprise offers SSO with SAML2 and OIDC, SLAs and an account manager.

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## Where InboxSpec differs

-   The wait happens on the server, over REST and MCP alike, so a test or agent does not run its own polling loop. There is no hidden time window.
-   Hitting your allowance produces a quota error you can act on, not a timeout that looks like your application never sent the email.
-   Custom receiving domains start on the $19 plan rather than Enterprise.

Some limits apply to InboxSpec whichever tool you compare it with:

-   InboxSpec is new. Production opened in October 2026, so it has no long operating record.
-   It only receives and captures email. It does not send to real recipients, test SMS, render emails in real mail clients or offer annual billing.
-   It has no SSO, SOC 2 report or uptime SLA.
-   REST and hosted [MCP](https://www.inboxspec.com/docs/markdown/mcp.md) are public. The [TypeScript SDK and CLI](https://www.inboxspec.com/docs/markdown/installation.md) are reviewed release archives that are not yet on a public package registry.

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## Switching

The [Mailosaur migration guide](https://www.inboxspec.com/docs/markdown/migrate-from-mailosaur.md) maps `messages.get`, search criteria, codes and links to InboxSpec's wait.

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## Sources

All pages read on 24 October 2026. InboxSpec figures come from the [pricing page](https://www.inboxspec.com/pricing) and the [wait guide](https://www.inboxspec.com/docs/markdown/waits.md).

-   [Mailosaur pricing](https://mailosaur.com/pricing)
-   [Mailosaur usage limits](https://mailosaur.com/docs/managing-your-account/usage-limits)
-   [Mailosaur custom domains](https://mailosaur.com/docs/managing-your-account/managing-domains)
-   [Mailosaur API reference](https://mailosaur.com/docs/api)
-   [Mailosaur Node.js client README](https://github.com/mailosaur/mailosaur-node)

Mailosaur, MailSlurp, testmail.app and Mailtrap are trademarks of their owners. InboxSpec is not affiliated with them.