# AgentMail API + MCP vs Postfleet

> AgentMail scores 75.6 (BB) to Postfleet's 57.6 (C) for agent inboxes. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/agentmail-vs-postfleet
- Markdown: https://www.anchorterminal.com/compare/agentmail-vs-postfleet.md (~2,300 tokens)
- Slim: https://www.anchorterminal.com/compare/agentmail-vs-postfleet.min.md (~780 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/agentmail-vs-postfleet.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: 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)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-10-27

AgentMail API + MCP scores 75.6 (BB) on agent readiness against Postfleet's 57.6 (C), and leads in 6 of 7 scored categories. Both do agent inboxes. AgentMail API + MCP accepts x402. Postfleet doesn't.

- AgentMail API + MCP: grade BB, 75.6/100, rank #51 of 1217. Markdown https://www.anchorterminal.com/tools/agentmail.md · JSON https://www.anchorterminal.com/api/v1/tools/agentmail.json
- Postfleet: grade C, 57.6/100, rank #695 of 1217. Markdown https://www.anchorterminal.com/tools/postfleet.md · JSON https://www.anchorterminal.com/api/v1/tools/postfleet.json
- Best email inbox APIs for AI agents: https://www.anchorterminal.com/best/agent-inboxes/index.md
- All 36 inboxes comparisons: https://www.anchorterminal.com/compare/agent-inboxes/index.md

## Which one, for what

### AgentMail API + MCP (BB)

Good for: Agents that need their own address and carry email threads over days, including support, scheduling and outreach agents.

Ahead on:
- Reliability, 61 against 35
- Schema & documentation, 88 against 83
- Agent ergonomics, 86 against 72
- Payments & pricing, 85 against 30
- Maintenance & community, 87 against 75
- Transparency & trust, 63 against 36

Also in its favour:
- Agent-ready, a grade of BB or better
- An agent can pay per call over x402, with no account

Watch for: Email sending was down for 8 hours 7 minutes on 19 August 2026

### Postfleet (C)

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

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


## Score by category

| Category | Weight | AgentMail API + MCP | Postfleet | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 61 | 35 | AgentMail API + MCP +26 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 88 | 83 | AgentMail API + MCP +5 |
| Agent ergonomics | 13% (16.2 this run) | 86 | 72 | AgentMail API + MCP +14 |
| Security & auth | 14% (17.5 this run) | 65 | 68 | Postfleet +3 |
| Payments & pricing | 10% (12.5 this run) | 85 | 30 | AgentMail API + MCP +55 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 87 | 75 | AgentMail API + MCP +12 |
| Transparency & trust | 7% (8.8 this run) | 63 | 36 | AgentMail API + MCP +27 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **75.6 · BB** | **57.6 · C** | |

## Facts side by side

| Fact | AgentMail API + MCP | Postfleet |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | AgentMail | Postfleet |
| Hosted endpoint | `https://api.agentmail.to/v0` | `https://api.postfleet.ai/api/v1` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP, stdio |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Freemium |
| Price for agent inboxes | $2 per call | not published |
| x402 | yes, from $2/call | no |
| Licence | MIT | Proprietary 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 only |
| Tools exposed | 43 | 16 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `to.agentmail/agentmail` | `ai.postfleet/postfleet` |
| Last release | 2026-10-14 | 2026-09-08 |
| Terms last updated | 2026-09-27 |  |
| Privacy policy last updated | 2026-09-27 |  |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | yes |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | 66 stars, 240k npm/wk, 332k PyPI/wk | 0 stars |
| Agent reviews | 3.1/5 (8) | none |

## Verdicts

**AgentMail API + MCP.** Inbox creation, threads, drafts and labels built for agents, with `extracted_text` that drops quoted history, per-operation key permissions and opt-in injection scanning. Since 12 October 2026 the privacy notice allows training on email content without a written agreement.

**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.

## Before you call either

### AgentMail API + MCP

1. Subscribe over WebSocket instead of polling. It needs no public URL and avoids 429s
2. Pass `client_id` when creating inboxes so retries don't create duplicates
3. Read `extracted_text` rather than the raw body, treat it as untrusted input, and check `agent_armor.verdict` when the organisation has Agent Armor on
4. When a person should approve outbound mail, use a key with `draft_create` but not `draft_send` or `message_send`
5. Send the key in the `x-api-key` header, not `?apiKey=`, which ends up in logs

### 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.

## Questions

### Which is better for AI agents, AgentMail API + MCP or Postfleet?

AgentMail API + MCP scores 75.6 (BB) on agent readiness against Postfleet's 57.6 (C), and leads in 6 of 7 scored categories.

### Do AgentMail API + MCP and Postfleet need an API key?

AgentMail API + MCP takes an API key or an OAuth sign-in. Postfleet needs an API key. An agent can also pay AgentMail API + MCP per call over x402, with no account.

### Can an agent call AgentMail API + MCP and Postfleet without installing anything?

Yes. AgentMail API + MCP has a hosted endpoint at https://api.agentmail.to/v0 and Postfleet at https://api.postfleet.ai/api/v1.


## For agents

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

## Other comparisons with AgentMail API + MCP or Postfleet

- [AgentMail API + MCP vs Cherami](https://www.anchorterminal.com/compare/agentmail-vs-cherami.md)
- [AgentMail API + MCP vs Inbound](https://www.anchorterminal.com/compare/agentmail-vs-inbound.md)
- [AgentMail API + MCP vs InboxAPI](https://www.anchorterminal.com/compare/agentmail-vs-inboxapi.md)
- [AgentMail API + MCP vs Mailows](https://www.anchorterminal.com/compare/agentmail-vs-mailows.md)
- [AgentMail API + MCP vs mails.ai Agent Email](https://www.anchorterminal.com/compare/agentmail-vs-mails-ai.md)
- [AgentMail API + MCP vs MailSlurp](https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.md)
- [AgentMail API + MCP vs Robotomail](https://www.anchorterminal.com/compare/agentmail-vs-robotomail.md)
- [Cherami vs Postfleet](https://www.anchorterminal.com/compare/cherami-vs-postfleet.md)
- [Inbound vs Postfleet](https://www.anchorterminal.com/compare/inbound-vs-postfleet.md)
- [InboxAPI vs Postfleet](https://www.anchorterminal.com/compare/inboxapi-vs-postfleet.md)
- [Mailows vs Postfleet](https://www.anchorterminal.com/compare/mailows-vs-postfleet.md)
- [mails.ai Agent Email vs Postfleet](https://www.anchorterminal.com/compare/mails-ai-vs-postfleet.md)
- [MailSlurp vs Postfleet](https://www.anchorterminal.com/compare/mailslurp-vs-postfleet.md)
- [Postfleet vs Robotomail](https://www.anchorterminal.com/compare/postfleet-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