Head to head · Mailbox access · October 2026 research run

email-agent-mcp vs Zoho Mail API

email-agent-mcp scores 65.9 (B) on agent readiness against Zoho Mail API's 49.6 (D), and leads in 5 of 7 scored categories. Zoho Mail API leads on transparency & trust. Both do mailbox access.

Best mailbox access APIs for AI agents · All 55 mailboxes comparisons

Which one, for what

email-agent-mcp B

Best for A person who wants an agent working in their own Outlook mailbox, or reading and drafting in Gmail, with guardrails.

Ahead on

  • Reliability, 50 against 42
  • Schema & documentation, 79 against 45
  • Agent ergonomics, 79 against 56
  • Payments & pricing, 60 against 30
  • Maintenance & community, 84 against 33

Also in its favour

  • Runs on your own machine
  • Open source

Watch for

Pre-1.0, and every commit is by one maintainer

Zoho Mail API D

Best 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

  • Transparency & trust, 73 against 42

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.

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community email-agent-mcp +51

email-agent-mcp 84

v0.5.0 was tagged and published on 5 November 2026 (30). Nine npm releases in the 90 days from 8 August, v0.3.0 to v0.5.0 (20). Pull requests up to #234 merged in the history, all by the one maintainer; issue responses couldn't be read through GitHub's API that day (10 of 25). io.github.UseJunior/email-agent-mcp is in the official MCP registry with 0.5.0 marked latest (15). CI, commitlint, semgrep and Codecov workflows (9 of 10). Total 84.

Zoho Mail API 33

Zoho keeps no API changelog, so recency rests on What's New entries for functions the REST API serves, dated by month only. What's New (Last-Modified 2 November 2026) lists from August to October 2026 two such entries, subfolders in the Archive folder (August, Folders API) and flagged emails added as tasks (October, Tasks API). The rest are web, mobile or admin-console functions the API doesn't serve (TLS policies, MTA-STS, display and settings screens). October lies 4 to 34 days back, within 90 but not shown within 30 (20). Two entries in the window from 6 August, fewer than three (0). The pricing page states support by email, chat and phone around the clock, and the changelog is public. The community forum wasn't tested for replies (9 of 15 for a closed service). No REST SDK. A Java command line tool and the MCP server are official. The MCP registry was not checked (4 of 15). No public repository, package or CI was found (0 of 10). 20 + 0 + 9 + 4 + 0 = 33.

Schema & documentation email-agent-mcp +34

email-agent-mcp 79

Tools are defined with typed input schemas that the MCP SDK publishes as JSON Schema (25). README in five languages, AGENTS.md, CLAUDE.md and GEMINI.md; no llms.txt, which a local server doesn't need (5 of 10). The README's tool table marks each tool read, write or destructive and states provider limits, such as Gmail deletes removing drafts only (15 of 20). Typed inputs with options such as list_style (12 of 15). Setup examples per client and documented error behaviour, such as NOT_SUPPORTED on Gmail and sanitised errors (10 of 15). Semver tags and GitHub Releases (12 of 15). Total 79.

Zoho Mail API 45

Graded on the REST API. No OpenAPI or similar file was found in the docs or under the zoho organisation on GitHub. The MCP tool definitions sit in a signed-in console and were not read (0 of 25). https://www.zoho.com/mail/help/llms.txt indexes a Markdown twin of every reference page (10). Each page states the purpose and names the call that supplies each ID, with little on when not to use a call (13 of 20). Parameters are listed with a type, a mandatory mark, allowed values and defaults, in prose only. Many PUT calls share one URL and differ by a mode field, and sample responses carry numbers and booleans as strings (9 of 15). Every page has a curl sample and a sample response. Errors are one shared list of seven status codes, with nothing per endpoint (9 of 15). The path has no version. What's New is a product changelog dated by month, and no API changelog was found (4 of 15).

Transparency & trust Zoho Mail API +31

email-agent-mcp 42

Apache-2.0 with a LICENSE file (30). SECURITY.md says tokens and mail are handled locally over stdio with no network listener, and the broker README says mail never reaches the broker and refresh tokens aren't stored. The broker has no published privacy policy (22 of 30). No deprecation policy (0). No telemetry was found in the README or package manifests, and none is stated either way (10 of 20). Total 62.

Zoho Mail API 73

The editorial half. A closed service under the Zoho Terms of Service, last updated 2 March 2022, and a Zoho Mail usage policy updated 2 September 2026. No source repository (15 of 30). The privacy policy of 22 December 2025 says Zoho does not sell personal information, and that account data leaves the active database at a clean-up run every six months after termination and backups three months later. It also says anonymised crops of service data are used to improve algorithms and that staff may manually verify emails reported as spam, while the Zoho Mail privacy page says Zoho will never read a customer's emails. The DPA is sent on request by email (21 of 30). No API deprecation policy or dated notices were found (0 of 20). A sub-processor page exists, but its list loads by script and was not read. The data centre page names 20 sites and the certifications of each (15 of 20). The provenance half is computed from the provenance block.

Payments & pricing email-agent-mcp +30

email-agent-mcp 60

Free, Apache-2.0 software with nothing to buy, scored 20 + 20 + 20 by the self-hosted rule. No payment protocol (0 of 40). Total 60.

Zoho Mail API 30

No x402, MPP or L402 (0 of 40). Plan prices are rendered on the pricing page without a login, $1 to $6 a user a month billed yearly, with API access included and no per-call price (10 of 20). Mail Free covers five users with no card, in some regions only, and the highest paid edition has a 15-day trial with no card (20). A person signs up in a browser, registers an OAuth client in the API console and approves scopes (0 of 20). 0 + 10 + 20 + 0 = 30.

Agent ergonomics email-agent-mcp +23

email-agent-mcp 79

27 tools in the full profile, the 11 to 30 band, plus the observe profile as a read-only subset (20 of 25). List and search tools filter and page; we read the tool table, not every parameter (16 of 20). Errors are sanitised and use stable reasons such as NOT_SUPPORTED, failing closed before a Gmail mutation (15 of 20). readOnlyHint and destructiveHint on the tools in source; sends take no idempotency key (16 of 20). One npx command and a setup wizard for OAuth and mailbox choice; TypeScript only (12 of 15). Total 79.

Zoho Mail API 56

Graded on the REST API. List and search return a summary per message and the body is a separate call, with limit from 1 to 200 and a default of 10. There is no field selection. In MCP the owner chooses which tools a server carries, and the tool count is not published (17 of 25). start and limit, filters for folder, read status, flag, label, thread and attachments, three sort keys and a search syntax (18 of 20). Errors carry a status code, a description and a moreInfo message. Seven codes are documented, with no list of messages or recovery steps (10 of 20). No idempotency key or conditional write was found, so a retried send can go out twice. Delete moves to Trash unless expunge=true. MCP annotations were not read (5 of 20). Send needs only fromAddress and toAddress, and defaults are stated. No REST SDK in any language, tokens last an hour, hosts differ by data centre, and reading a body needs an account ID, a folder ID and a message ID (6 of 15).

Reliability email-agent-mcp +8

email-agent-mcp 50

Graded with the lines for local packages and stdio MCP servers. Installs from the official npm package email-agent-mcp with npx, CI runs on Node 20 (20). A CI workflow with Vitest tests, Codecov and a spec-coverage gate; the run results weren't readable through GitHub's API that day, so partial (20 of 25). Open crash and regression issues couldn't be read because GitHub's API refused our requests for its rate limit (0, unchecked). Semver tags from v0.1.7 to v0.5.0 and auto-categorised GitHub Releases as the changelog, with no breaking changes marked in what we read (10 of 15). Pre-1.0 (0). Total 50.

Zoho Mail API 42

Graded on the REST API, read with the hosted lines. status.zoho.com redirects to us.zohostatus.com, which listed components for Zoho Mail, mail listing, IMAP, POP, SMTP and the MX host on 9 October. The status-page line keeps its 20, as on the other Zoho listings. us.zohostatus.com now answers robots.txt with an access-denied page, so the 9 October incident readings are struck and no history is readable (5). The getting started guide (Last-Modified 8 January 2026) says each API has its own rate limit and gives no numbers. Sending limits are published, 50 to 500 external emails an hour and 1,000 internal. Kept as a partial (7). The response code list has no 429, and no Retry-After, backoff guidance or idempotency key was found. The guide says only that the response will say when a limit is exceeded, which is no handling guidance (0). The pricing page lists a 99.9% uptime guarantee with no SLA document, measurement or credit terms, and a listed SLA figure with no document gives 0 in this run (0). The API carries no beta or preview label (10). 20 + 5 + 7 + 0 + 0 + 10 = 42.

Score by category

CategoryWeight this runemail-agent-mcpZoho Mail APIEdge
Reliability16%205042email-agent-mcp +8
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27945email-agent-mcp +34
Agent ergonomics13%16.27956email-agent-mcp +23
Security & auth14%17.56767even
Payments & pricing10%12.56030email-agent-mcp +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88433email-agent-mcp +51
Transparency & trust7%8.84273Zoho Mail API +31
Negative events≤1500
TotalB 65.9/100D 49.6/100

Facts side by side

Factemail-agent-mcpZoho Mail API
KindMCP serverHTTP API
VendorUseJuniorZoho
Hosted endpointno (local only)no (local only)
TransportsstdioHTTP
AuthOAuthOAuth
PricingFreeFreemium
x402nono
LicenceApache-2.0Proprietary service under the Zoho Terms of Service and the Zoho Mail usage policy. No source repository was found
Tools exposed27none
Read-only variant documentedyesno
llms.txtnoyes
MCP registryio.github.UseJunior/email-agent-mcpnot listed
Last release2026-11-05none
Terms last updatedno document linked2022-03-02
Privacy policy last updatedno document linked2025-12-22
Customer content may train modelsnot read yetyes
Terms restrict automated accessnot read yetnot found in the text
Terms restrict benchmarkingnot read yetyes
Terms or service can change without noticenot read yetnot found in the text
Arbitration or class-action waivernot read yetnot found in the text
Popularity394 npm/wknone

How the scores have moved

Verdicts

email-agent-mcp

A local MCP server for a person's own Outlook or Gmail mailbox with careful defaults, a read-only scope profile, send allowlists, gated deletes and annotated tools, released weekly under Apache-2.0. It is pre-1.0 from one maintainer, Gmail lacks label and move support, and Gmail sign-in relies on UseJunior's hosted broker.

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

email-agent-mcp

  1. Start with get_mailbox_status, then list_emails or search_emails before reading whole threads
  2. Ask the person to set the send allowlist before planning any send_email or reply_to_email
  3. Prefer create_draft and let the person send, unless they asked for sending
  4. Expect NOT_SUPPORTED for label, flag, mark-read and move on Gmail, and don't request gmail.modify to work around it
  5. Don't plan deletes; they need an operator environment variable and a caller flag

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, email-agent-mcp or Zoho Mail API?

email-agent-mcp scores 65.9 (B) on agent readiness against Zoho Mail API's 49.6 (D), and leads in 5 of 7 scored categories. Zoho Mail API leads on transparency & trust.

Do email-agent-mcp and Zoho Mail API need an API key?

Both use an OAuth sign-in.

Can an agent call email-agent-mcp and Zoho Mail API without installing anything?

email-agent-mcp runs on your own machine, with no hosted endpoint listed. No hosted endpoint is listed for Zoho Mail API.

Are email-agent-mcp and Zoho Mail API open source?

email-agent-mcp is open source (Apache-2.0). No open-source release is listed for Zoho Mail API.

Other comparisons with email-agent-mcp or Zoho Mail API

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