Compare and switch
InboxSpec vs Mailtrap Email Sandbox
A dated comparison of sandbox volume, per-inbox storage, polling and receiving domains, including where Mailtrap is better.
Every Mailtrap fact on this page comes from its public pricing page and documentation on that date, listed under 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 If something here is wrong or out of date, tell us at hello@inboxspec.com and we will correct it.
This page compares Mailtrap Email Sandbox. Mailtrap's sending products are priced separately and do a different job.
At a glance
| Topic | Mailtrap Email Sandbox | InboxSpec |
|---|---|---|
| Price, monthly billing | Free $0, Basic $17, Team $42, Business $123, Enterprise $498. Annual billing lowers these to $14, $34, $99 and $399 a month. | Free $0 (500 messages/month), Starter $19 (10,000), Developer $49 (50,000), Team $129 (150,000). Monthly billing only. |
| Volume | 50, 500, 5,000, 50,000 test emails/month, and unlimited on Enterprise. | 500, 10,000, 50,000 and 150,000 messages/month. |
| Stored per inbox | 10, 50, 200, 600 or 1,000 emails per sandbox. At the limit the oldest emails are removed first. | No per-inbox count. Messages are kept for the plan's retention period: 7, 7, 14 or 30 days. |
| People | 1, 3, 5, 50 users, and unlimited on Enterprise. | 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. |
| Receiving address | A dedicated sandbox address on Mailtrap's own domain from Basic upward. Its docs do not describe a custom receiving domain for Sandbox. | Shared domain on Free. Custom receiving domains on every paid plan: 1 on Starter, 3 on Developer, 10 on Team. |
| Waiting | No blocking wait is documented. Messages are read by polling the API, and its MCP server has no wait tool. | 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. |
| Send rate | A per-plan limit per 10 seconds. Mail over it is refused with an SMTP 550 error. | Waiting is exempt from request rate limits. Message volume counts against the monthly allowance. |
Where Mailtrap is the better choice
- Message analysis on captured mail: its Sandbox is built for checking HTML rendering and spam scores, and its MCP server exposes spam-score and HTML-analysis tools.
- One account also covers real sending, marketing email and inbound parsing, with an MCP server that spans all of them.
- Mailtrap lists GDPR, ISO 27001 and SOC 2 Type 2 on every Sandbox plan, and Enterprise adds SSO and audit logs.
- A free, open-source local sandbox for development.
Where InboxSpec differs
- At least 10 times the included volume at a similar price: 10,000 messages for $19 against Basic's 500 for $17, or 50,000 for $49 against Team's 5,000 for $42.
- Messages are not evicted when an inbox fills, so a parallel test run does not lose its own evidence.
- A blocking wait over REST and MCP, and custom receiving domains, so you can test signup flows that refuse shared testing domains.
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 are public. The TypeScript SDK and CLI are reviewed release archives that are not yet on a public package registry.
Sources
All pages read on 24 October 2026. InboxSpec figures come from the pricing page and the wait guide.
Mailosaur, MailSlurp, testmail.app and Mailtrap are trademarks of their owners. InboxSpec is not affiliated with them.