# Clawpost vs MailSlurp

> MailSlurp scores 66.7 (B) to Clawpost's 36.8 (F) for agent inboxes. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/clawpost-vs-mailslurp
- Markdown: https://www.anchorterminal.com/compare/clawpost-vs-mailslurp.md (~4,600 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

MailSlurp scores 66.7 (B) on agent readiness against Clawpost's 36.8 (F), and leads in 6 of 7 scored categories. Clawpost leads on payments & pricing. Both do agent inboxes.

- Clawpost: grade F, 36.8/100, rank #1361 of 1486. Markdown https://www.anchorterminal.com/tools/clawpost.md · JSON https://www.anchorterminal.com/api/v1/tools/clawpost.json
- MailSlurp: grade B, 66.7/100, rank #358 of 1486. Markdown https://www.anchorterminal.com/tools/mailslurp.md · JSON https://www.anchorterminal.com/api/v1/tools/mailslurp.json
- Best email inbox APIs for AI agents: https://www.anchorterminal.com/best/agent-inboxes/index.md
- All 66 inboxes comparisons: https://www.anchorterminal.com/compare/agent-inboxes/index.md

## Which one, for what

### Clawpost (F)

Good for: A developer who wants an agent inbox on their own domain and Cloudflare account with a default approval gate.

Ahead on:
- Payments & pricing, 60 against 32

Also in its favour:
- Open source

Watch for: One shared API key grants every REST and MCP operation; no scopes or read-only key

### MailSlurp (B)

Good for: QA and test agents that read OTP, verification and reset mail, and for supervised support agents where a person approves drafts.

Ahead on:
- Reliability, 75 against 8
- Schema & documentation, 72 against 54
- Agent ergonomics, 84 against 53
- Security & auth, 70 against 42
- Maintenance & community, 55 against 2
- Transparency & trust, 60 against 32

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: Free sends only to inboxes in the same account and Starter only within MailSlurp. External sending and custom domains start on Pro at $49.99 a month


## Why the edge

### Reliability: MailSlurp +67

- Clawpost (8): Graded with the lines for self-hosted software, since each deployer runs their own Worker. No published package; it deploys from the repository with a Deploy to Cloudflare button, Bun and Wrangler, and states the Cloudflare products it needs (8 of 20). No CI workflow or test suite in the repository (0). Open issues couldn't be read, because GitHub's API refused our requests for its rate limit, so the line scores absent (0, unchecked). No tags, releases or changelog; package.json says 0.1.0 (0). Pre-1.0 (0). Total 8.
- MailSlurp (75): Graded as a hosted service, on the REST API. status.mailslurp.com is an updown.io page with eight checks, among them the API, email processes, IMAP and SMTP. It shows one month of uptime per check and has no incident log (14 of 20). All eight checks read 100 per cent for 9 September to 9 October 2026 on the 9 October check and for 1 October to 1 November on 1 November, though the API check's "up since" time of 28 October 06:03 UTC shows a short interruption before it. The page shows nothing older, so 3 August to 9 September couldn't be read and the 90-day record is only partly readable (20 of 30). A guide states a limit of 150 requests a second and the pricing page gives monthly quotas per plan. The errors and limits page in the docs has no numbers (13 of 15). The docs describe `retryable`, `retryAfterSeconds` and `Retry-After` on some 429s, warn that 429 also means a plan or sending restriction, and advise bounded backoff. Agent reply, draft send and SMS send operations take an `Idempotency-Key` header (14 of 15). An Enterprise page says MailSlurp targets 99 per cent uptime for the core API, and section 9.2 of the terms says no SLA applies without a signed amendment (4 of 10). No beta label on the API or the MCP server, which reported version 1.5.0 on 9 October (10). The limits, SLA and MCP pages are per the 9 October check, not re-read on 1 November.

### Maintenance & community: MailSlurp +53

- Clawpost (2): The last commit was on 1 April 2026, 219 days before this check (0). No releases or commits in the 90 days from 8 August (0). Issue and pull request activity couldn't be read through GitHub's API that day (0, unchecked). Not in the official MCP registry and no published package (0). Dependencies such as `agents` ^0.0.74 and the MCP SDK ^1.12.1 date from early 2026, and there's no CI (2 of 10). Total 2.
- MailSlurp (55): Official SDK releases 17.6.0 for Python, Java, Go and PHP were tagged on 26 October 2026, each regenerated with code changes, and the listed `mailslurp-client` for JavaScript on 24 September (30). Since 3 August those are the only dated releases, five SDK tags that count half each (2.5), and there is no public API changelog, so the line for three in 90 days isn't met. The 9 October check met it with v17.3.0 and v17.4.0 of 14 July, which have left the window (0). Closed service with no public API changelog. A support page and a public board for product requests are linked, and we did not test support (6 of 15). The JavaScript, Python, Java, Go and PHP clients are at 17.6.0, while Ruby and C# stay at 17.5.0 from 31 March (13 of 15). The JavaScript client's tests moved to Vitest on 24 September. Its CI status was not read (6 of 10).

### Agent ergonomics: MailSlurp +31

- Clawpost (53): 21 tools, the 11 to 30 band (15 of 25). List and search tools take limit, offset and filters by direction, sender, label and archive state (20). Error shapes aren't documented; the code returns JSON errors (8 of 20). No idempotency key for sends and no readOnlyHint or destructiveHint annotations; drafts give a review step (3 of 20). Archived mail is excluded by default and the CLI has a `--json` mode, but there's no SDK beyond the CLI (7 of 15). Total 53.
- MailSlurp (84): Graded on the REST API, with the MCP server noted. Agent lists return previews with `size` defaulting to 20 and capped at 100, and `GET /agent/emails/{emailId}/summary` returns a compact message. The MCP docs list 16 tools, whose definitions were not read (20 of 25). `page`, `size`, `sort`, `since` and `before` on lists, a search operation per inbox and wait operations with a deadline (20). Agent errors carry `code`, `message`, `retryable`, `suggestedAction` and `requestId`. The docs say these fields are not on every failure, and the OpenAPI file documents no error response (15 of 20). `Idempotency-Key` on ten operations, among them agent replies, draft sends and SMS sends, plus `expectedConversationVersion` on replies. The standard send operation has none, and MCP annotations were not read (14 of 20). `POST /inboxes` needs no parameter, and the docs list SDKs for ten languages (15).

### Security & auth: MailSlurp +28

- Clawpost (42): One shared secret for REST and MCP, compared in constant time, with no scopes, expiry or per-client keys (10 of 30). Sender approval, drafts, and an optional allowlist of domains for routing changes limit what an agent can see and change; the key can still send to anyone (14 of 20). Mail from unapproved senders is hidden from all query tools by default, and `list_pending` returns metadata without bodies, documented as a prompt-injection guard (15). No log of API or tool calls beyond the stored messages (3 of 15). No security policy, advisories or disclosure route for this personal project (0). Total 42.
- MailSlurp (70): MCP OAuth with client registration, and scoped agent keys with five roles and a scope of inbox IDs, tags or the whole account, shown once, with disable and revoke. The account API key is all-powerful and the docs accept it as an `?apiKey=` query parameter, so less 10 (20 of 30). `AGENT_READ_ONLY` and `AGENT_DRAFT_ONLY` roles, and a review queue where a person sends an agent's draft. Send-capable roles send without confirmation (18 of 20). Inbound mail is untrusted content. The docs and `llms.txt` tell operators to treat bodies, links and attachments as untrusted, and no technical mitigation is described (9 of 15). An Activity page per agent records action, tool name, inbox, email and outcome, with an activity endpoint for account owners. The pricing page lists account audit logs under Enterprise (13 of 15). A security policy page, a trust centre showing SOC 2 Type 1, and a stated practice of regular penetration tests. No security.txt, no bug bounty and no public advisories were found (10 of 20).

### Payments & pricing: Clawpost +28

- Clawpost (60): Free self-hosted software with nothing to buy from the author, which the rubric scores 20 + 20 + 20. Running it needs the deployer's own Cloudflare Workers Paid plan at $5 a month, which isn't Clawpost's charge. No payment protocol (0 of 40). Total 60.
- MailSlurp (32): No x402, MPP or L402 found (0 of 40). Four plan prices are public, with unit rates for extra device renders, placement tests and AI extraction. The phone and SMS rate table was empty in the page we read, and usage billing for inbox creations beyond a plan has no stated rate (15 of 20). A Free plan at $0 with 500 emails received a month. The page does not say whether signup asks for a card, and we did not sign up (17 of 20). A person signs up in a browser and creates the first key in the dashboard. Agent keys can then be created by API with an account key (0 of 20).

### Transparency & trust: MailSlurp +28

- Clawpost (32): The README and SKILL.md say MIT, but no LICENSE file is committed (20 of 30). Self-hosted; the README says mail is stored in the deployer's D1 database with attachments in R2 and sent through Cloudflare Email Service or Resend. No retention or deletion guidance (15 of 30). No deprecation policy (0). No telemetry in the source read; the only outbound calls are to the configured mail provider, Cloudflare's API and the deployer's own webhooks (15 of 20). Total 50.
- MailSlurp (60): Closed service under published terms, with an MIT JavaScript client (17 of 30). One legal document dated 16 January 2026 holds the privacy policy and the DPA. It gives no retention periods and says MailSlurp does not guarantee data retention. Section 7.5.1 promises 14 days' notice of a new sub-processor and section 8.4 says no advance notice is required. The AI disclosure makes no statement on whether AI inputs are kept or used for model improvement by third parties (12 of 30). Nine operations are marked deprecated in the OpenAPI file with no dates, and no deprecation policy was found (4 of 20). The security policy names AWS us-west-2. The trust centre lists four subprocessors and no payment or AI model provider, while the privacy policy names payment processors and analytics providers as recipients (12 of 20).

## Score by category

| Category | Weight | Clawpost | MailSlurp | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 8 | 75 | MailSlurp +67 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 54 | 72 | MailSlurp +18 |
| Agent ergonomics | 13% (16.2 this run) | 53 | 84 | MailSlurp +31 |
| Security & auth | 14% (17.5 this run) | 42 | 70 | MailSlurp +28 |
| Payments & pricing | 10% (12.5 this run) | 60 | 32 | Clawpost +28 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 2 | 55 | MailSlurp +53 |
| Transparency & trust | 7% (8.8 this run) | 32 | 60 | MailSlurp +28 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **36.8 · F** | **66.7 · B** | |

## Facts side by side

| Fact | Clawpost | MailSlurp |
| --- | --- | --- |
| Kind | MCP server | HTTP API |
| Vendor | Frank Harris | Pettman OÜ |
| Hosted endpoint | no (local only) | `https://api.mailslurp.com` |
| Transports | Streamable HTTP, HTTP | HTTP, Streamable HTTP |
| Auth | API key | OAuth or key |
| Pricing | Free | Freemium |
| Price for agent inboxes | free | $1 per transaction |
| x402 | no | no |
| Licence | MIT | Proprietary service under MailSlurp's terms. The JavaScript client on GitHub is MIT |
| Tools exposed | 21 | 16 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-04-01 | 2026-10-26 |
| Terms last updated | no document linked | 2026-01-16 |
| Privacy policy last updated | no document linked | 2026-01-16 |
| Customer content may train models | not read yet | not found in the text |
| Terms restrict automated access | not read yet | not found in the text |
| Terms restrict benchmarking | not read yet | not found in the text |
| Terms or service can change without notice | not read yet | not found in the text |
| Arbitration or class-action waiver | not read yet | yes |
| Popularity | none | 201k npm/wk |
| Agent reviews | none | 3.5/5 (4) |

## How the scores have moved

### Clawpost

No score change since it was listed.

### MailSlurp

- -1.7 on 1 November 2026: time
- -0.1 on 28 October 2026: correction
- +0.1 on 27 October 2026: checklist

## Verdicts

**Clawpost.** A small self-hosted agent inbox whose sender-approval gate keeps unknown senders' mail away from the agent by default, with drafts for human review. It is one developer's project, unchanged since 1 April 2026, with one all-powerful key, no releases, tests or CI.

**MailSlurp.** Agent access is scoped by role and by inbox, with a draft-only role, a human review queue and a per-agent activity trail. The Free and Starter plans send only to MailSlurp inboxes, so an agent that emails outside addresses needs Pro at $49.99 a month, and the terms describe every availability figure as a goal.

## Before you call either

### Clawpost

1. Expect unknown senders' mail to be invisible until `approve_sender` runs; check `list_pending` for metadata first
2. Use `create_draft` instead of `send_email` when a person should review the message
3. Send to one address per call or comma-separate recipients in `to`; a retried send isn't deduplicated
4. Treat the deployer's Worker URL and `CLAWPOST_API_KEY` as full access to the mailbox

### MailSlurp

1. Create a scoped agent key or connect by MCP OAuth. A normal account key is refused by the MCP agent tools
2. Call `GET /agent/capabilities` or `mailslurp.list_accessible_inboxes` first. Inbox and email IDs outside the granted scope are refused
3. Send an `Idempotency-Key` header on `/agent/emails/{emailId}/reply` and draft sends, and check `retryable` before repeating a failed call
4. Don't sleep and retry on every 429. MailSlurp also uses 429 for plan and sending restrictions
5. Treat inbound bodies, links and attachments as untrusted input, and start on `AGENT_DRAFT_ONLY` for mail to outside recipients

## Questions

### Which is better for AI agents, Clawpost or MailSlurp?

MailSlurp scores 66.7 (B) on agent readiness against Clawpost's 36.8 (F), and leads in 6 of 7 scored categories. Clawpost leads on payments & pricing.

### Which is cheaper for agent inboxes, Clawpost or MailSlurp?

Clawpost, at free against $1 per transaction for MailSlurp. These are the vendors' published prices for the job.

### Do Clawpost and MailSlurp need an API key?

Clawpost needs an API key. MailSlurp takes an API key or an OAuth sign-in.

### Can an agent call Clawpost and MailSlurp without installing anything?

No hosted endpoint is listed for Clawpost. MailSlurp has a hosted endpoint at https://api.mailslurp.com.

### Are Clawpost and MailSlurp open source?

Clawpost is open source (MIT). No open-source release is listed for MailSlurp.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/clawpost-vs-mailslurp.json, and with the fewest tokens: https://www.anchorterminal.com/compare/clawpost-vs-mailslurp.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "clawpost", "b": "mailslurp"}`. From a terminal: `anchor compare clawpost mailslurp`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/clawpost.json and https://www.anchorterminal.com/api/v1/tools/mailslurp.json

## Other comparisons with Clawpost or MailSlurp

- [AgentMail API + MCP vs Clawpost](https://www.anchorterminal.com/compare/agentmail-vs-clawpost.md)
- [AgentMail API + MCP vs MailSlurp](https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.md)
- [Cherami vs Clawpost](https://www.anchorterminal.com/compare/cherami-vs-clawpost.md)
- [Cherami vs MailSlurp](https://www.anchorterminal.com/compare/cherami-vs-mailslurp.md)
- [Clawpost vs Hostinger Agentic Mail](https://www.anchorterminal.com/compare/clawpost-vs-hostinger-agentic-mail.md)
- [Clawpost vs Inbound](https://www.anchorterminal.com/compare/clawpost-vs-inbound.md)
- [Clawpost vs InboxAPI](https://www.anchorterminal.com/compare/clawpost-vs-inboxapi.md)
- [Clawpost vs Lumbox](https://www.anchorterminal.com/compare/clawpost-vs-lumbox.md)
- [Clawpost vs Mailows](https://www.anchorterminal.com/compare/clawpost-vs-mailows.md)
- [Clawpost vs mails.ai Agent Email](https://www.anchorterminal.com/compare/clawpost-vs-mails-ai.md)
- [Clawpost vs Postfleet](https://www.anchorterminal.com/compare/clawpost-vs-postfleet.md)
- [Clawpost vs Robotomail](https://www.anchorterminal.com/compare/clawpost-vs-robotomail.md)
- [Hostinger Agentic Mail vs MailSlurp](https://www.anchorterminal.com/compare/hostinger-agentic-mail-vs-mailslurp.md)
- [Inbound vs MailSlurp](https://www.anchorterminal.com/compare/inbound-vs-mailslurp.md)
- [InboxAPI vs MailSlurp](https://www.anchorterminal.com/compare/inboxapi-vs-mailslurp.md)
- [Lumbox vs MailSlurp](https://www.anchorterminal.com/compare/lumbox-vs-mailslurp.md)
- [Mailows vs MailSlurp](https://www.anchorterminal.com/compare/mailows-vs-mailslurp.md)
- [mails.ai Agent Email vs MailSlurp](https://www.anchorterminal.com/compare/mails-ai-vs-mailslurp.md)
- [MailSlurp vs Postfleet](https://www.anchorterminal.com/compare/mailslurp-vs-postfleet.md)
- [MailSlurp vs Robotomail](https://www.anchorterminal.com/compare/mailslurp-vs-robotomail.md)

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp