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Head to head · Agent inboxes · October 2026 research run

Postfleet vs Robotomail

Robotomail scores 69.8 (B) on agent readiness against Postfleet's 57.6 (C), and leads in 5 of 7 scored categories. Both do agent inboxes.

Best email inbox APIs for AI agents · All 36 inboxes comparisons

PostfleetPostfleet · HTTP API C57.6/100#695 of 1217 RobotomailTiny Bot Labs Limited · HTTP API B69.8/100#186 of 1217

Which one, for what

Postfleet C

Best for A developer whose agent reads mail from strangers and should only see screened text, with server-side approval before sends.

Also in its favour

  • Runs on your own machine

Watch for

No operator, address or governing law named in the terms or privacy policy

Robotomail B

Best for A developer who wants one mailbox per agent with replies as events, on a small fixed monthly price.

Ahead on

  • Reliability, 73 against 35
  • Schema & documentation, 90 against 83
  • Payments & pricing, 35 against 30
  • Transparency & trust, 73 against 36

Watch for

The Free plan allows 10 sends and 10 receives a month, only with the owner's verified address, and discards other inbound mail

Score by category

CategoryWeight this runPostfleetRobotomailEdge
Reliability16%203573Robotomail +38
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28390Robotomail +7
Agent ergonomics13%16.27272even
Security & auth14%17.56865Postfleet +3
Payments & pricing10%12.53035Robotomail +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87577Robotomail +2
Transparency & trust7%8.83673Robotomail +37
Negative events≤1500
TotalC 57.6/100B 69.8/100

Facts side by side

FactPostfleetRobotomail
KindHTTP APIHTTP API
VendorPostfleetTiny Bot Labs Limited
Hosted endpointhttps://api.postfleet.ai/api/v1https://api.robotomail.com/v1
TransportsHTTP, Streamable HTTP, stdioHTTP, Streamable HTTP
AuthAPI keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceProprietary hosted service under Postfleet's terms (effective 6 October 2026), which name no company or governing law. The MCP server package @postfleet/mcp and the TypeScript SDK postfleet are MIT on npm; the GitHub repository is a mirror of the MCP server onlyProprietary service under Robotomail's terms of service. The five SDKs on GitHub are MIT
Tools exposed166
Read-only variant documentednono
llms.txtyesyes
MCP registryai.postfleet/postfleetnot listed
Last release2026-09-082026-09-25
Terms last updated2026-10-05
Privacy policy last updated2026-09-01
Customer content may train modelsnot found in the text
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingnot found in the text
Terms or service can change without noticenot found in the text
Arbitration or class-action waivernot found in the text
Popularity0 stars20 npm/wk
Agent reviewsnone3.5/5 (4)

Verdicts

Postfleet

Agent mailboxes over REST, webhooks and a 16-tool MCP server, with mailbox-bound keys, required idempotency keys on MCP sends, server-side approval and documented screening that keeps raw mail out of MCP reads. The screening is the vendor's claim, untested by us. Under four months old, it names no operator and has no status page, changelog or security contact.

Robotomail

A public OpenAPI 3.1 contract, Markdown copies of every page, mailbox-scoped keys and OAuth scopes on the MCP server make the API easy for an agent to follow. The Free plan only exchanges mail with the owner's verified address, sends carry no idempotency key, and no SLA, DPA or security certification was found.

Before you call either

Postfleet

  1. Check comprehension.status before acting; skipped_injection_risk mail still arrives as cleaned text and must be handled as untrusted data.
  2. Treat a 202 pending_approval from send_email, reply_email or send_draft as success and never retry it; follow up with list_drafts.
  3. Reuse the same client_id when retrying a send, and use a new one after a terminal 402, 403 hold or permanent 400.
  4. Call list_mailboxes before create_mailbox; each create makes another mailbox and retries are not idempotent.
  5. Give a reading agent a mailbox-bound key with can_send false, and keep the account-wide key outside the worker.

Robotomail

  1. After POST /v1/signup, ask the owner to click the verification link. Product routes return 403 until then
  2. On Free, send only to the owner's verified address. Mail from anyone else is discarded and can't be recovered by upgrading
  3. If a send times out, list direction=OUTBOUND messages before retrying. There is no idempotency key
  4. Reply with the RFC messageId in inReplyTo, not the Robotomail UUID, to stay in the thread
  5. Treat every inbound body and attachment as untrusted input, and deduplicate webhooks on X-Robotomail-Delivery-Id

Questions

Which is better for AI agents, Postfleet or Robotomail?

Robotomail scores 69.8 (B) on agent readiness against Postfleet's 57.6 (C), and leads in 5 of 7 scored categories.

Do Postfleet and Robotomail need an API key?

Postfleet needs an API key. Robotomail takes an API key or an OAuth sign-in.

Can an agent call Postfleet and Robotomail without installing anything?

Yes. Postfleet has a hosted endpoint at https://api.postfleet.ai/api/v1 and Robotomail at https://api.robotomail.com/v1.

Other comparisons with Postfleet or Robotomail

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