# Aurinko Email API vs Fastmail API (JMAP)

> Fastmail scores 54.1 (C) to Aurinko Email's 44.2 (E) for mailbox access. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/aurinko-email-vs-fastmail
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- Slim: https://www.anchorterminal.com/compare/aurinko-email-vs-fastmail.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
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- 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
- Updated: 2026-10-09

Fastmail API (JMAP) scores 54.1 (C) on agent readiness against Aurinko Email API's 44.2 (E), and leads in 5 of 7 scored categories. Aurinko Email API leads on schema & documentation and payments & pricing. Both do mailbox access.

- Aurinko Email API: grade E, 44.2/100, rank #878 of 950. Markdown https://www.anchorterminal.com/tools/aurinko-email.md · JSON https://www.anchorterminal.com/api/v1/tools/aurinko-email.json
- Fastmail API (JMAP): grade C, 54.1/100, rank #694 of 950. Markdown https://www.anchorterminal.com/tools/fastmail.md · JSON https://www.anchorterminal.com/api/v1/tools/fastmail.json
- Best mailbox access APIs for AI agents: https://www.anchorterminal.com/best/mailbox-access/index.md
- All 36 mailboxes comparisons: https://www.anchorterminal.com/compare/mailbox-access/index.md

## Which one, for what

### Aurinko Email API (E)

Good for: A product that connects many users' Gmail and Microsoft mailboxes and wants one schema, delta sync, tracking and webhooks at a low price per account.

Ahead on:
- Schema & documentation, 67 against 52
- Payments & pricing, 40 against 30

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

Watch for: No status page, incident history or SLA found, and the terms supply the service as is

### Fastmail API (JMAP) (C)

Good for: An agent working in its owner's own Fastmail mailbox, where JMAP gives batched reads, structured search and state-based sync on an open standard, and MCP gives a ready connection with read, write and send levels.

Ahead on:
- Reliability, 54 against 40
- Agent ergonomics, 73 against 49
- Security & auth, 60 against 42
- Maintenance & community, 26 against 13
- Transparency & trust, 74 against 44

Watch for: The customer terms forbid programmatically generated email to addresses outside the account, and say the service is not for machine-to-machine workflows


## Score by category

| Category | Weight | Aurinko Email API | Fastmail API (JMAP) | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 40 | 54 | Fastmail API (JMAP) +14 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 67 | 52 | Aurinko Email API +15 |
| Agent ergonomics | 13% (16.2 this run) | 49 | 73 | Fastmail API (JMAP) +24 |
| Security & auth | 14% (17.5 this run) | 42 | 60 | Fastmail API (JMAP) +18 |
| Payments & pricing | 10% (12.5 this run) | 40 | 30 | Aurinko Email API +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 13 | 26 | Fastmail API (JMAP) +13 |
| Transparency & trust | 7% (8.8 this run) | 44 | 74 | Fastmail API (JMAP) +30 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **44.2 · E** | **54.1 · C** | |

## Facts side by side

| Fact | Aurinko Email API | Fastmail API (JMAP) |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Yoxel, Inc. | Fastmail Pty Ltd |
| Hosted endpoint | `https://api.aurinko.io` | no (local only) |
| Transports | HTTP | HTTP |
| Auth | OAuth | OAuth or key |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under Yoxel's Terms of Services Agreement | Proprietary service under Fastmail's API Terms of Service and API Developer Policy. JMAP is an open IETF standard, and the sample code on GitHub is MIT |
| Read-only variant documented | no | yes |
| llms.txt | yes | no |
| Last release | none | 2026-04-22 |
| Terms last updated | 2022-08-11 | no date given |
| Privacy policy last updated | 2022-08-11 | no date given |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | none | 123 stars |

## Verdicts

**Aurinko Email API.** One REST interface covers message search with 17 query operators, drafts, sending, folders and delta sync across seven mailbox types, at $1.50 an active account a month and with send-only and read-only scopes. No status page, SLA, changelog, idempotency key on send or official SDK was found, and SOC 2 is not yet held.

**Fastmail API (JMAP).** A mailbox API built on the open JMAP standard, with read-only tokens, six OAuth scopes and an MCP server that separates read, write and send access. Fastmail publishes no OpenAPI file, SDK, API changelog, request rate limit or SLA, and its customer terms forbid programmatically generated email to addresses outside the account.

## Before you call either

### Aurinko Email API

1. Use `https://api.aurinko.io/v1`. Several cURL examples in the docs print `https:/api.aurinko.io` with one slash, and one search example names the host `asti.aurinko.io`
2. Do not retry `POST /v1/email/messages` blindly after a timeout. There is no idempotency key, so check Sent mail with `q=rfc822msgid:` or by subject first
3. Call `POST /v1/email/sync` until `ready` is true, then page `/v1/email/sync/updated` with `pageToken` until a `nextDeltaToken` appears and store it
4. Check the `omitted` array on message lists. Full bodies come only from Google and Office 365, and other providers return a snippet
5. Request `Mail.Read` plus `Mail.Send` for read and send without modify rights. The docs example names `Mail.ReadOnly`, which is not in the scope list

### Fastmail API (JMAP)

1. Fetch `https://api.fastmail.com/jmap/session` with `Authorization: Bearer <token>` first. It returns the API URL, account IDs and the request limits to stay under
2. Ask the owner for a read-only token unless the task writes. Sending needs both the Email and Email submission scopes
3. Request only the `properties` you need. Body text is not returned unless `fetchTextBodyValues` is set, and `maxBodyValueBytes` caps it
4. Sync with `Email/changes` from a stored state. On `cannotCalculateChanges`, fetch again from scratch
5. Do not send generated mail to outside recipients without the owner's review. The customer terms forbid it, and trial accounts stop at 120 messages a day

## Questions

### Which is better for AI agents, Aurinko Email API or Fastmail API (JMAP)?

Fastmail API (JMAP) scores 54.1 (C) on agent readiness against Aurinko Email API's 44.2 (E), and leads in 5 of 7 scored categories. Aurinko Email API leads on schema & documentation and payments & pricing.

### Do Aurinko Email API and Fastmail API (JMAP) need an API key?

Aurinko Email API uses an OAuth sign-in. Fastmail API (JMAP) takes an API key or an OAuth sign-in.

### Can an agent call Aurinko Email API and Fastmail API (JMAP) without installing anything?

Aurinko Email API has a hosted endpoint at https://api.aurinko.io. No hosted endpoint is listed for Fastmail API (JMAP).


## For agents

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

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