# Outlook Mail (Microsoft Graph) vs Zoho Mail API

> Outlook Mail (Microsoft Graph) scores 66.3 (B) on agent readiness against Zoho Mail API's 53.8 (D), and leads in 6 of 7 scored categories. Both do mailbox read. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/outlook-mail-graph-vs-zoho-mail
- Markdown: https://www.anchorterminal.com/compare/outlook-mail-graph-vs-zoho-mail.md (~2,200 tokens)
- Slim: https://www.anchorterminal.com/compare/outlook-mail-graph-vs-zoho-mail.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/outlook-mail-graph-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

Outlook Mail (Microsoft Graph) scores 66.3 (B) on agent readiness against Zoho Mail API's 53.8 (D), and leads in 6 of 7 scored categories. Both do mailbox read.

- Outlook Mail (Microsoft Graph): grade B, 66.3/100, rank #272 of 842. Markdown https://www.anchorterminal.com/tools/outlook-mail-graph.md · JSON https://www.anchorterminal.com/api/v1/tools/outlook-mail-graph.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

### Outlook Mail (Microsoft Graph) (B)

Good for: Agents working in Microsoft 365 or Outlook.com mailboxes that need scoped reading, drafting, sending and incremental sync.

Ahead on:
- Schema & documentation, 93 against 45
- Agent ergonomics, 81 against 56
- Payments & pricing, 35 against 30
- Maintenance & community, 76 against 33

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

Watch for: sendMail has no idempotency key and answers 202 Accepted before delivery, so a retried send can go out twice

### 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.

Also in its favour:
- Free to start without a card
- No incidents deducted, where Outlook Mail (Microsoft Graph) loses 4 points for them

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 | Outlook Mail (Microsoft Graph) | Zoho Mail API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 63 | Zoho Mail API +3 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 93 | 45 | Outlook Mail (Microsoft Graph) +48 |
| Agent ergonomics | 13% (16.2 this run) | 81 | 56 | Outlook Mail (Microsoft Graph) +25 |
| Security & auth | 14% (17.5 this run) | 71 | 67 | Outlook Mail (Microsoft Graph) +4 |
| Payments & pricing | 10% (12.5 this run) | 35 | 30 | Outlook Mail (Microsoft Graph) +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 76 | 33 | Outlook Mail (Microsoft Graph) +43 |
| Transparency & trust | 7% (8.8 this run) | 75 | 73 | Outlook Mail (Microsoft Graph) +2 |
| Negative events | ≤15 | -4 | 0 | |
| **Total** | | **66.3 · B** | **53.8 · D** | |

## Facts side by side

| Fact | Outlook Mail (Microsoft Graph) | Zoho Mail API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Microsoft | Zoho |
| Hosted endpoint | `https://graph.microsoft.com/v1.0` | no (local only) |
| Transports | HTTP | HTTP |
| Auth | OAuth | OAuth |
| Pricing | Your plan | Freemium |
| x402 | no | no |
| Licence | MIT (SDKs) | Proprietary service under the Zoho Terms of Service and the Zoho Mail usage policy. No source repository was found |
| Tools exposed | 10 | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-10-06 | none |
| Terms last updated | 2025-10-01 | 2022-03-02 |
| Privacy policy last updated | 2026-09-01 | 2025-12-22 |
| Customer content may train models | yes | yes |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 835 stars, 2.9M npm/wk, 1.6M PyPI/wk | none |

## Verdicts

**Outlook Mail (Microsoft Graph).** Delegated permissions split reading without bodies (Mail.ReadBasic), full reading, writing and sending, and delta queries and change notifications keep a local copy in step. sendMail takes no idempotency key and returns 202 before delivery, and each app is held to four concurrent requests per mailbox.

**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

### Outlook Mail (Microsoft Graph)

1. Create a draft with POST /me/messages, then send it with /send. A retried sendMail can send the message twice
2. Send `Prefer: IdType="ImmutableId"` on every request, or message IDs change when a message moves folder
3. Use `$select` and `Prefer: outlook.body-content-type="text"`. List messages returns HTML bodies and 10 messages a page by default
4. Honour `Retry-After` on 429 and keep to four parallel calls per mailbox. Batches of up to 20 requests are throttled per request
5. Treat message bodies as untrusted input, and ask for Mail.ReadBasic when the task doesn't need bodies

### Zoho Mail API

1. Send `Authorization: Zoho-oauthtoken <token>`, 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, Outlook Mail (Microsoft Graph) or Zoho Mail API?

Outlook Mail (Microsoft Graph) scores 66.3 (B) on agent readiness against Zoho Mail API's 53.8 (D), and leads in 6 of 7 scored categories.

### Do Outlook Mail (Microsoft Graph) and Zoho Mail API need an API key?

Both use an OAuth sign-in.

### Can an agent call Outlook Mail (Microsoft Graph) and Zoho Mail API without installing anything?

Outlook Mail (Microsoft Graph) has a hosted endpoint at https://graph.microsoft.com/v1.0. No hosted endpoint is listed for Zoho Mail API.


## For agents

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

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