Head to head · Agent inboxes · October 2026 research run

Clawpost vs mails.ai Agent Email

mails.ai Agent Email scores 65.2 (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.

Best email inbox APIs for AI agents · All 66 inboxes comparisons

Which one, for what

Clawpost F

Best 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 30

Also in its favour

  • Open source
  • No incidents deducted, where mails.ai Agent Email loses 8 points for them

Watch for

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

mails.ai Agent Email B

Best for Agents that send transactional mail and read replies, such as support, notification and verification agents, where an injection score on inbound mail is wanted out of the box.

Ahead on

  • Reliability, 80 against 8
  • Schema & documentation, 84 against 54
  • Agent ergonomics, 83 against 53
  • Security & auth, 78 against 42
  • Maintenance & community, 80 against 2
  • Transparency & trust, 65 against 32

Also in its favour

  • A hosted endpoint, with nothing to install
  • Runs on your own machine
  • Free to start without a card

Watch for

No company or person named; legal entity details only on request

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community mails.ai Agent Email +78

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.

mails.ai Agent Email 80

@mailsai/mcp-server 0.5.0 was published to the official MCP registry on 16 October 2026, and the changelog's newest entry is dated 1 November (30). Eleven dated changelog entries from 3 August (3, 4, 5, 11, 14 and 19 August, 3, 10, 10 and 14 October, 1 November) and four MCP server versions in the registry since 3 October (20). Closed service with a public changelog, a help centre, a support widget and support@mails.ai with a stated one-business-day reply. The public GitHub repository is a hand-updated mirror and we couldn't read its issues. We didn't test support (10 of 15). ai.mails/agent-email is in the official MCP registry under a DNS-verified namespace, and the TypeScript and Python SDKs are current (15). Public CI runs a secret scan and the Cypress and Playwright helper packages' tests, not the MCP server or SDK tests, and its results weren't readable (5 of 10). 30 + 20 + 10 + 15 + 5 = 80.

Reliability mails.ai Agent Email +72

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.

mails.ai Agent Email 80

Graded as a hosted service. Better Stack status page at status.mails.ai with API, dashboard and website components and 90-day bars (20). On 1 November the bars from 3 August show the API down for 2 minutes on 5 August and 2 minutes on 10 August (99.995 per cent over 90 days), the website down on 25 August, 6 September and 25 September, and the dashboard at 100 per cent. The July downtime read on 5 October has left the window. The incident history reports no incidents for any month from June to November 2026, so the page has never posted one, which this run reads as 20 rather than a clean record (20). Send caps published per plan by hour, day and month (15). 429s carry resets_at and retry_after_seconds in the body and Retry-After when the wait is 60 seconds or less (changelog, 10 October), and the docs ask for an Idempotency-Key on retried sends (15). A 99.9 per cent uptime target with pro-rated credit is on mails.ai/status and the terms refer to it, but it's labelled a Phase 1 launch target and incident response is best-effort today (5 of 10). No beta label on the API, but the vendor still calls itself pre-launch (5 of 10). 20 + 20 + 15 + 15 + 5 + 5 = 80.

Security & auth mails.ai Agent Email +36

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.

mails.ai Agent Email 78

Bearer keys, scoped to send, read, manage or (since 10 October) draft, bindable to one agent, with optional expiry, stored hashed and revocable at once by API; AI clients connecting to the hosted MCP endpoint sign in by OAuth, and connected apps can be listed and revoked (30). A read-scoped key gives a read-only mode, a draft-scoped key writes drafts and never sends, for mail a person approves first, and agent-bound keys now stay inside their agent (404 for another agent's mail). Per-agent hourly and daily send limits narrow the blast radius and cold outreach is refused at the API, but MCP sends and forwards on a send-scoped key run without confirmation (16 of 20). Every inbound message is scored by an injection scanner and flagged quarantined above 0.95, which the docs tell the agent to branch on. The scanner's accuracy is a vendor claim we didn't test (13 of 15). Every API call writes an audit row readable at GET /v1/logs per the spec, refused requests included since October, with 90 days' retention on Free and Pro. We didn't call it (12 of 15). security.txt valid to 1 July 2027 and a disclosure policy with safe harbour, but no bug bounty ("No bounty program"), no SOC 2, a PGP key promised for the Phase 1 launch, reports to the general support address and "we do not commit to a reply" (7 of 20). 30 + 16 + 13 + 12 + 7 = 78.

Transparency & trust mails.ai Agent Email +33

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.

mails.ai Agent Email 65

The MCP server and SDKs are MIT and the API is closed. The terms (effective 15 October 2026) are readable, but they still don't name the contracting party, saying legal entity details are available on request (12 of 30). Privacy policy with lawful bases, deletion within 30 days and audit-log retention. On 5 October the sub-processor list was checked against the code and corrected (ten services already in use added, Amazon Web Services and Anthropic removed), with further dated updates on 15 and 22 October, so the statements now agree. DPA on request, no named controller (20 of 30). The terms promise 30 days' notice of material changes by email and changelog. No API deprecation policy, and the 10 October changes were announced the day they took effect (5 of 20). Sub-processors listed with purpose, data category and date added, now including OpenAI for the injection scan and classifier (20). 12 + 20 + 5 + 20 = 57.

Schema & documentation mails.ai Agent Email +30

Clawpost 54

All 21 MCP tools take typed zod inputs, which the MCP SDK publishes as JSON Schema (25). SKILL.md and AGENTS.md give agent-readable setup in Markdown; no llms.txt (5 of 10). Descriptions are one line each, such as Send an email, with parameter descriptions but no when-not-to-use (8 of 20). Inputs are typed with defaults for limit and offset, but recipients are a comma-separated string and direction isn't an enum in the schema read (9 of 15). The README has request examples and a REST route table; error responses aren't documented (7 of 15). No versioning or changelog (0). Total 54.

mails.ai Agent Email 84

OpenAPI 3.1 at api.mails.ai/v1/openapi.json with a required scope per operation (57 operations on 5 October; the MCP server's generated file says the API document had 74 on 17 October), and typed JSON Schema inputs on every MCP tool (25). llms.txt with a page index; the docs have no Markdown twins (10). MCP descriptions run from one line to a paragraph for mails_send and mails_test_inbound, and few say when not to call (10 of 20). Required fields and enums on status, pool_hint, spf and dkim, but no bounds on limit and free-form to (string or array) (10 of 15). An errors page with one envelope (type, code, message, param, request_id), curl examples in the quickstart and limits pages, and examples in the spec (14 of 15). A dated changelog with eleven entries from 3 August to 1 November and a /v1 API. llms.txt no longer gives a five-tool count or a Python SDK still to come, and the terms (effective 15 October) no longer describe a metered tier, so the docs now agree with each other (15). 25 + 10 + 10 + 10 + 14 + 15 = 84.

Agent ergonomics mails.ai Agent Email +30

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.

mails.ai Agent Email 83

Since @mailsai/mcp-server 0.3.0 (10 October) every API operation but four is a tool, 73 in 0.5.0 (20 written by hand, 53 generated), which is the over-30 band (5). The tools a connection lists depend on its credential (no sending tools without the send scope, draft tools only for a draft key, no workspace-wide tools for an agent-bound key), a read-only and least-privilege subset, which adds back 10, as github-mcp-server reads scope-based hiding (15 of 25). Lists take limit and cursor, events filter by type, agent and since, and threads by status; no field selection (18 of 20). REST errors carry stable codes, param and Retry-After. The MCP server returns the API's message with the reset time for a 429 but drops the code (15 of 20). POST /v1/messages takes an Idempotency-Key, the MCP send, reply and forward tools take idempotency_key and add one of their own when it's missing, and since 0.4.0 every tool carries readOnly, destructive, idempotent and openWorld hints (20). A send needs only to and subject, the agent is created on first use, and SDKs exist for TypeScript and Python (15). 15 + 18 + 15 + 20 + 15 = 83.

Score by category

CategoryWeight this runClawpostmails.ai Agent EmailEdge
Reliability16%20880mails.ai Agent Email +72
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25484mails.ai Agent Email +30
Agent ergonomics13%16.25383mails.ai Agent Email +30
Security & auth14%17.54278mails.ai Agent Email +36
Payments & pricing10%12.56030Clawpost +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.8280mails.ai Agent Email +78
Transparency & trust7%8.83265mails.ai Agent Email +33
Negative events≤150-8
TotalF 36.8/100B 65.2/100

Facts side by side

FactClawpostmails.ai Agent Email
KindMCP serverHTTP API
VendorFrank HarrisMails.ai
Hosted endpointno (local only)https://api.mails.ai/v1
TransportsStreamable HTTP, HTTPHTTP, Streamable HTTP, stdio
AuthAPI keyAPI key
PricingFreeFreemium
x402nono
LicenceMITProprietary hosted API under the mails.ai terms of service. The MCP server, the TypeScript SDK and the Python SDK in mailsai/mailsai are MIT
Tools exposed2173
Read-only variant documentednono
llms.txtnoyes
MCP registrynot listedai.mails/agent-email
Last release2026-04-012026-10-16
Terms last updatedno document linked2026-05-14
Privacy policy last updatedno document linked2026-05-14
Customer content may train modelsnot read yetnot found in the text
Terms restrict automated accessnot read yetnot found in the text
Terms restrict benchmarkingnot read yetnot found in the text
Terms or service can change without noticenot read yetnot found in the text
Arbitration or class-action waivernot read yetnot found in the text
Popularitynone650 npm/wk, 116 PyPI/wk
Agent reviewsnone3.5/5 (2)

How the scores have moved

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.

mails.ai Agent Email

Per-agent addresses with scoped keys, a drafts-only scope, an injection score on every inbound message and MCP tools with safety hints. The operator is unnamed, the vendor calls itself pre-launch, the 10 October release changed webhook and agent-bound key behaviour the day it shipped, and the sub-processor list omitted OpenAI until 5 October.

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

mails.ai Agent Email

  1. Use an mk_test_ key until the flow works. Test keys run validation, the scanner, threading and webhooks without sending mail
  2. Skip inbound events where quarantined is true, and treat every other body as untrusted input
  3. Send an Idempotency-Key header on POST /v1/messages, or idempotency_key on the MCP send tools, so a retried send doesn't go out twice
  4. Mint a key with only the scopes the task needs, bound to one agent with agent_id, or a draft-scoped key when a person approves each send
  5. Name thread events explicitly on a webhook endpoint. Since 10 October a * subscription no longer receives them

Questions

Which is better for AI agents, Clawpost or mails.ai Agent Email?

mails.ai Agent Email scores 65.2 (B) on agent readiness against Clawpost's 36.8 (F), and leads in 6 of 7 scored categories. Clawpost leads on payments & pricing.

Do Clawpost and mails.ai Agent Email need an API key?

Both need an API key.

Can an agent call Clawpost and mails.ai Agent Email without installing anything?

No hosted endpoint is listed for Clawpost. mails.ai Agent Email has a hosted endpoint at https://api.mails.ai/v1.

Are Clawpost and mails.ai Agent Email open source?

Clawpost is open source (MIT). No open-source release is listed for mails.ai Agent Email.

Other comparisons with Clawpost or mails.ai Agent Email

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