# Fastmail API (JMAP) vs Zoho Mail API > Fastmail API (JMAP) and Zoho Mail API score within a point of each other on agent readiness, 54.1 (C) and 53.8 (D). Zoho Mail API leads on reliability, security & auth and maintenance & community. Both do mailbox read. Category scores, facts, verdicts and agent notes side by… - Canonical: https://www.anchorterminal.com/compare/fastmail-vs-zoho-mail - Markdown: https://www.anchorterminal.com/compare/fastmail-vs-zoho-mail.md (~2,200 tokens) - Slim: https://www.anchorterminal.com/compare/fastmail-vs-zoho-mail.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts) - JSON: https://www.anchorterminal.com/compare/fastmail-vs-zoho-mail.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 - Updated: 2026-10-09 Fastmail API (JMAP) and Zoho Mail API score within a point of each other on agent readiness, 54.1 (C) and 53.8 (D). Zoho Mail API leads on reliability, security & auth and maintenance & community. Both do mailbox read. - Fastmail API (JMAP): grade C, 54.1/100, rank #620 of 842. Markdown https://www.anchorterminal.com/tools/fastmail.md · JSON https://www.anchorterminal.com/api/v1/tools/fastmail.json - Zoho Mail API: grade D, 53.8/100, rank #626 of 842. Markdown https://www.anchorterminal.com/tools/zoho-mail.md · JSON https://www.anchorterminal.com/api/v1/tools/zoho-mail.json ## Which one, for what ### 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: - Schema & documentation, 52 against 45 - Agent ergonomics, 73 against 56 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 ### Zoho Mail API (D) Good for: An agent working inside its owner's Zoho Mail mailbox or administering a Zoho Mail organisation, where narrow scopes and the MCP server keep access small. Ahead on: - Reliability, 63 against 54 - Security & auth, 67 against 60 - Maintenance & community, 33 against 26 Also in its favour: - Free to start without a card Watch for: The Zoho Mail usage policy, updated 2 September 2026, lists automated, bulk and transactional emails among uses that are not allowed. ## Score by category | Category | Weight | Fastmail API (JMAP) | Zoho Mail API | Edge | | --- | --- | --- | --- | --- | | Reliability | 16% (20 this run) | 54 | 63 | Zoho Mail API +9 | | Performance | 10%, pending | pending | pending | not scored in this run | | Schema & documentation | 13% (16.2 this run) | 52 | 45 | Fastmail API (JMAP) +7 | | Agent ergonomics | 13% (16.2 this run) | 73 | 56 | Fastmail API (JMAP) +17 | | Security & auth | 14% (17.5 this run) | 60 | 67 | Zoho Mail API +7 | | Payments & pricing | 10% (12.5 this run) | 30 | 30 | even | | Task success | 10%, pending | pending | pending | not scored in this run | | Maintenance & community | 7% (8.8 this run) | 26 | 33 | Zoho Mail API +7 | | Transparency & trust | 7% (8.8 this run) | 74 | 73 | Fastmail API (JMAP) +1 | | Negative events | ≤15 | 0 | 0 | | | **Total** | | **54.1 · C** | **53.8 · D** | | ## Facts side by side | Fact | Fastmail API (JMAP) | Zoho Mail API | | --- | --- | --- | | Kind | HTTP API | HTTP API | | Vendor | Fastmail Pty Ltd | Zoho | | Hosted endpoint | no (local only) | no (local only) | | Transports | HTTP | HTTP | | Auth | OAuth or key | OAuth | | Pricing | Paid | Freemium | | x402 | no | no | | Licence | 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 | Proprietary service under the Zoho Terms of Service and the Zoho Mail usage policy. No source repository was found | | Read-only variant documented | yes | no | | llms.txt | no | yes | | Last release | 2026-04-22 | none | | Terms last updated | no date given | 2022-03-02 | | Privacy policy last updated | no date given | 2025-12-22 | | Customer content may train models | not found in the text | yes | | Terms restrict automated access | not found in the text | 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 | not found in the text | not found in the text | | Popularity | 123 stars | none | ## Verdicts **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. **Zoho Mail API.** A REST API over a Zoho Mail mailbox with OAuth scopes that narrow to one resource and one operation, plus an MCP server launched in 2026. Zoho publishes no OpenAPI file, SDK, request rate limit or API changelog, and its usage policy bars automated email. ## Before you call either ### Fastmail API (JMAP) 1. Fetch `https://api.fastmail.com/jmap/session` with `Authorization: Bearer ` 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 ### Zoho Mail API 1. Send `Authorization: Zoho-oauthtoken `, not `Bearer`. The token response says `Bearer`, but the OAuth guide says the Mail API requires the Zoho prefix. 2. Use the host for the account's data centre, such as `mail.zoho.eu` or `mail.zoho.in`. Call `GET /api/accounts` first for the `accountId` every mailbox call needs. 3. Reading a message body needs both `folderId` and `messageId`. List and search calls return a summary only, 10 messages by default and 200 at most. 4. Request `ZohoMail.messages.READ` alone for a reading agent. Add `CREATE` only when it must send, and leave `DELETE` out unless required. 5. Refresh the access token every hour, and post OAuth parameters in the request body where the server accepts it, to keep secrets out of URLs. ## Questions ### Which is better for AI agents, Fastmail API (JMAP) or Zoho Mail API? Fastmail API (JMAP) and Zoho Mail API score within a point of each other on agent readiness, 54.1 (C) and 53.8 (D). Zoho Mail API leads on reliability, security & auth and maintenance & community. ### Do Fastmail API (JMAP) and Zoho Mail API need an API key? Fastmail API (JMAP) takes an API key or an OAuth sign-in. Zoho Mail API uses an OAuth sign-in. ### Can an agent call Fastmail API (JMAP) and Zoho Mail API without installing anything? No hosted endpoint is listed for Fastmail API (JMAP). No hosted endpoint is listed for Zoho Mail API. ## For agents - This comparison as JSON: https://www.anchorterminal.com/compare/fastmail-vs-zoho-mail.json, and with the fewest tokens: https://www.anchorterminal.com/compare/fastmail-vs-zoho-mail.min.md - Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "fastmail", "b": "zoho-mail"}`. From a terminal: `anchor compare fastmail zoho-mail` - Each listing in full: https://www.anchorterminal.com/api/v1/tools/fastmail.json and https://www.anchorterminal.com/api/v1/tools/zoho-mail.json ## Other comparisons with Fastmail API (JMAP) or Zoho Mail API - [EmailEngine vs Fastmail API (JMAP)](https://www.anchorterminal.com/compare/emailengine-vs-fastmail.md) - [EmailEngine vs Zoho Mail API](https://www.anchorterminal.com/compare/emailengine-vs-zoho-mail.md) - [Fastmail API (JMAP) vs Gmail API](https://www.anchorterminal.com/compare/fastmail-vs-gmail-api.md) - [Fastmail API (JMAP) vs Nylas Email API](https://www.anchorterminal.com/compare/fastmail-vs-nylas-email.md) - [Fastmail API (JMAP) vs Outlook Mail (Microsoft Graph)](https://www.anchorterminal.com/compare/fastmail-vs-outlook-mail-graph.md) - [Fastmail API (JMAP) vs Unipile](https://www.anchorterminal.com/compare/fastmail-vs-unipile.md) - [Gmail API vs Zoho Mail API](https://www.anchorterminal.com/compare/gmail-api-vs-zoho-mail.md) - [Nylas Email API vs Zoho Mail API](https://www.anchorterminal.com/compare/nylas-email-vs-zoho-mail.md) - [Outlook Mail (Microsoft Graph) vs Zoho Mail API](https://www.anchorterminal.com/compare/outlook-mail-graph-vs-zoho-mail.md) - [Unipile vs Zoho Mail API](https://www.anchorterminal.com/compare/unipile-vs-zoho-mail.md)