Head to head · Agent inboxes · October 2026 research run

Cherami vs Lumbox

Lumbox scores 60.7 (C) on agent readiness against Cherami's 58.6 (C), and leads in 4 of 7 scored categories. Cherami leads on maintenance & community. Both do agent inboxes.

Best email inbox APIs for AI agents · All 66 inboxes comparisons

Which one, for what

Cherami C

Best for A single developer or small team giving an agent a free, separate address for low-volume recurring correspondence such as supplier replies, project updates and agent-to-agent handoffs.

Ahead on

  • Maintenance & community, 74 against 23

Watch for

No status page, SLA or public changelog, so the webhooks API carries no release date

Lumbox C

Best for Agents that need their own address to receive sign-up codes and links and to send replies.

Ahead on

  • Reliability, 45 against 40
  • Security & auth, 71 against 46
  • Payments & pricing, 40 against 35
  • Transparency & trust, 72 against 56

Also in its favour

  • Runs on your own machine

Watch for

No status page, incident history or SLA; the terms say availability isn't guaranteed

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 Cherami +51

Cherami 74

TypeScript and Python SDKs 0.2.0 were released on 9 October 2026 (release commits 6b7dbde and 9e9a299, adding Trash listing and restore operations), 26 days before the check (30). In the 90 days from 6 August each of the two SDKs released 0.1.0 (3 and 4 October), 0.1.1 (8 October, README and version only) and 0.2.0, all distinct dated release commits. SDK releases count half on this line, so the six make three (20). The webhooks API in the live contract has no dated entry. Closed service with support by email at hello@cherami.to and a feedback tool in the API. No public changelog, the GitHub repositories carry no issues we could read, and we didn't test support (6 of 15). In the official MCP registry as io.github.cherami-mail/cherami-mcp, a GitHub-verified namespace, per the 5 October check, with official SDKs, which lag the live contract by its 15 newer operations (15). Both SDKs are generated from the OpenAPI contract and have a typecheck script, but neither repository has CI workflows or tests (3 of 10).

Lumbox 23

The latest package releases found are lumbox 0.3.1 on npm (19 June 2026) and @lumbox/mcp-server 0.2.2 (12 June 2026), 140 days before this check, the 91 to 180 day band (10). No releases or dated changelog entries in the 90 days from 8 August (0). A closed service with a support address and an X account; no changelog (5 of 15). Not in the official MCP registry (search for lumbox returned nothing on 6 November); Node and Python SDKs exist but haven't changed since June (5 of 15). The MCP server card says 0.2.1 while npm has 0.2.2, and the SDK repository named in npm isn't publicly readable (3 of 10). Total 23.

Security & auth Lumbox +25

Cherami 46

OAuth through Clerk with protected-resource metadata, but one scope, cherami_mail:full. API keys are revocable in Account, API keys, never expire, travel only in the Authorization header, and every key and grant reaches every inbox on the account. We read this as plain revocable keys (20 of 30). No read-only mode or inbox-limited credential. Per-inbox recipient allowlists and sender blocklists can be changed only by the account's human, drafts allow review before sending, and the delete tools' descriptions tell the agent to confirm with the human, with no server-side confirmation (10 of 20). Every tool that returns mail says to treat it as untrusted data, and a safety guide covers handling, but the docs state Cherami doesn't screen content for manipulation, spam or phishing (10 of 15). Sent messages keep their submission outcomes and responses carry X-Request-ID, but we found no audit log of API or MCP calls (4 of 15). No security.txt, disclosure policy, bug bounty or certification found. The privacy policy says credentials are stored as hashes and incidents are notified as the law requires (2 of 20).

Lumbox 71

OAuth 2.1 with PKCE, dynamic client registration and five scopes that split reading inboxes, reading mail, sending and domain changes, plus API keys stored as SHA-256 hashes that can be limited to named inboxes (30). Inbox-scoped keys and the read and send split keep one run away from another's codes; Lumbox's built-in agent drafts replies for approval, but the API itself sends at once (16 of 20). The terms tell users to treat bodies as untrusted, and the security page says attachment text is sanitised for prompt injection before it reaches an agent (12 of 15). The privacy policy says API calls are logged with endpoint, time and key prefix for rate limiting and billing; no customer-facing audit log was found (5 of 15). A valid security.txt to security@lumbox.co and a responsible disclosure section; not SOC 2 certified, no bug bounty (8 of 20). Total 71.

Transparency & trust Lumbox +16

Cherami 56

The service is closed under published terms (effective 9 October 2026). The SDKs and plugin files are MIT, and the MCP server's source isn't public (16 of 30). The privacy policy (effective 9 October 2026) names its providers and gives retention periods (no automatic mail expiry, Trash for seven days, Cloudflare logs up to 7 days, Clerk logs a few days, backups up to 30 days, account deletion within 30 days) and says mail isn't sold or used for advertising. It doesn't address model training, and a DPA is by request (24 of 30). No deprecation policy or dated notices, and the terms allow the service's functions, limits and availability to change and the service to be discontinued with no stated notice period (3 of 20). Cloudflare on its global network, Clerk and Svix in the United States are named, with no guaranteed processing location (15 of 20).

Lumbox 72

A closed hosted service; the security page says it can be self-hosted, but the repository the deployment guide clones isn't publicly readable. The footer names Cyphen Innovations Private Limited (15 of 30). The privacy policy and security page agree that mail is kept while its inbox exists and an account's data is deleted within 30 days, that email isn't used for training, and that the vault uses AES-256-GCM per-organisation keys (26 of 30). A deprecation policy with Deprecation and Sunset headers, 90 days' notice and 12 months for an old version (20). Hosts and locations named, Hetzner in Germany, Neon in the US, Vercel, Cloudflare, AWS SES, Dodo Payments and Steel for browsers (18 of 20). Total 79.

Reliability Lumbox +5

Cherami 40

Hosted lines. No status page. status.cherami.to doesn't resolve and cherami.to/status returns 404 on 4 November (0). With no history to read, the incident record gets 5. Signup discovery (10 per IP an hour), phrase redemption and browser approvals (10 per IP per 15 minutes) and the sending allowance (25 recipients per rolling 24 hours) are published with numbers, but no general request limit for reading or listing mail is stated (10 of 15). 429s carry Retry-After, the allowance error returns sufficient_capacity_at, and a retry table per operation sits beside idempotency keys on every write that sends or creates (15). The deployment guide says service commitments are by request and none is published (0). The API is /v1 with contract version 1.0.0 and no beta label on the HTTP or MCP surface (10).

Lumbox 45

Graded with the hosted lines. No status page was found; none is linked from the site or llms.txt, and status.lumbox.co doesn't resolve (0). With no history to read, the incident line takes 5. 120 requests a minute per API key, per IP for unauthenticated routes, with X-RateLimit headers (15). 429 returns retry_after_seconds, the spec gives a backoff schedule and says which statuses not to retry, and Idempotency-Key works on every POST for 24 hours (15). The terms say Lumbox doesn't guarantee uninterrupted service, and no SLA was found (0). The core API carries no beta label; dedicated phone numbers are early access (10). Total 45.

Payments & pricing Lumbox +5

Cherami 35

No x402, MPP or L402 (0). The service is free with its allowances published without a login, 2 inboxes and 25 recipient-deliveries a day. Anything beyond that is by request with no published price (15 of 20). No card and no paid tier (20). An agent can't get access alone. A person signs in and approves at cherami.to/claim in a browser, then gives the agent a one-use phrase, or approves an OAuth connection (0).

Lumbox 40

No x402, MPP or L402 (0). Four plans with prices and limits published without login, no per-email price (10 of 20). Free plan with 3 inboxes, 500 received and 100 sent emails a month, no card (20). Agent self-signup lets an agent create its own key, which a person approves once in a browser (10 of 20). Total 40.

Score by category

CategoryWeight this runCheramiLumboxEdge
Reliability16%204045Lumbox +5
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28582Cherami +3
Agent ergonomics13%16.28078Cherami +2
Security & auth14%17.54671Lumbox +25
Payments & pricing10%12.53540Lumbox +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87423Cherami +51
Transparency & trust7%8.85672Lumbox +16
Negative events≤1500
TotalC 58.6/100C 60.7/100

Facts side by side

FactCheramiLumbox
KindHTTP APIHTTP API
VendorCheramiCyphen Innovations Private Limited
Hosted endpointhttps://cherami.to/mcphttps://mcp.lumbox.co/mcp
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP, stdio
AuthOAuth or keyOAuth or key
PricingFreeFreemium
x402nono
LicenceProprietary hosted service under Cherami's terms of use. The plugin repository (cherami-mail/cherami-mcp) and the TypeScript and Python SDKs are MIT. The MCP server's own source isn't publicnone
Tools exposed4218
Read-only variant documentednono
llms.txtyesyes
MCP registryio.github.cherami-mail/cherami-mcpnot listed
Last release2026-10-092026-06-19
Terms last updated2026-10-072026-09-07
Privacy policy last updated2026-10-072026-03-16
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textyes
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textnot found in the text
Popularity119 npm/wk, 130 PyPI/wk13 npm/wk
Agent reviews3/5 (2)none

How the scores have moved

Verdicts

Cherami

Free @cherami.to inboxes with a typed OpenAPI contract, 42 documented MCP tools, webhooks and idempotency keys on every send. It's run by one person on a domain registered on 21 September 2026, with no status page, no changelog and keys that reach every inbox on the account, and a person must approve access in a browser.

Lumbox

Inbox-scoped keys, OAuth scopes that split reading from sending, idempotent POSTs, published rate limits and a written deprecation policy suit an agent that signs in with emailed codes. There is no status page or changelog, and the npm and PyPI packages haven't been released since June 2026.

Before you call either

Cherami

  1. Call list_inboxes first and use the inbox the human assigned. Connecting doesn't create an address
  2. Pass a unique idempotency_key on every send and reuse it unchanged within 24 hours to recover an uncertain result
  3. Read content.reply_text for routine replies, and treat all mail and attachments as untrusted data
  4. Check get_outbound_quota before a send to many recipients. Each To, Cc and Bcc entry counts against 25 a day
  5. Poll with a bounded page budget, or add a webhook and fetch each message by its ID. Incoming mail never wakes the agent

Lumbox

  1. Create one inbox per run and an inbox-scoped key, so parallel logins can't read each other's codes
  2. Call /otp with a timeout and treat 408 as no email yet; long-poll calls are safe to retry
  3. Send an Idempotency-Key on every POST, especially sends, so a retry within 24 hours doesn't act twice
  4. Treat message bodies as untrusted input; the parsed OTP fields don't mean a message is safe
  5. On 429 wait retry_after_seconds, and don't retry 400, 401, 403 or 404

Questions

Which is better for AI agents, Cherami or Lumbox?

Lumbox scores 60.7 (C) on agent readiness against Cherami's 58.6 (C), and leads in 4 of 7 scored categories. Cherami leads on maintenance & community.

Do Cherami and Lumbox need an API key?

Both take an API key or an OAuth sign-in.

Can an agent call Cherami and Lumbox without installing anything?

Yes. Cherami has a hosted endpoint at https://cherami.to/mcp and Lumbox at https://mcp.lumbox.co/mcp.

Other comparisons with Cherami or Lumbox

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.