Mailgun API + MCP vs MailPace

Mailgun API + MCP 83

OpenAPI 3.1 for send, validate, optimize and inspect, and every MCP tool takes a Zod schema built from it (25). llms.txt with about 145 links and Markdown pages (10). MCP tool descriptions are the OpenAPI operation summary, one line each, with nothing on when to use or avoid a tool (8). Inputs are typed from the spec, though the README says some edge-case parameters fall back to permissive validation (12). The spec carries request and error examples, and the server rewrites 400, 401, 403 and 404 into guidance (13). Dated release notes and a semver CHANGELOG for the MCP server (15).

MailPace 54

No OpenAPI or other machine-readable contract for the HTTPS API. The MCP server's 12 tools have typed zod inputs and output schemas, but that server isn't published yet, so partial credit (8 of 25). llms.txt answers 404 on mailpace.com and docs.mailpace.com, and no Markdown copies are served (0). The reference states what each endpoint does, and the introduction says when not to use it (transactional only, no batch, no static IPs) (12 of 20). Field tables give type, examples and required or optional, with enums for status, sort and direction and the 50-recipient cap in text (9 of 15). Examples in curl and six languages and a full table of error responses with messages, though several listed messages have a broken quote ({"error:"...) and the send reference says 30 MB where the home page says 25 MB (12 of 15). Version in the path with a promise that an old version runs until a published end-of-life date, and dated changelog posts (13 of 15). Total 54.

Mailgun API + MCP 74

HTTP Basic auth with a key. Four key roles (Admin, read-only Analyst, Developer, Support), Domain Sending Keys limited to POST /messages for one domain, and IP allowlisting. Rotation is advised but keys don't expire (28). The Analyst role is read-only, sending keys cover the least-privilege case, and the MCP server exposes no delete operations. Confirmation is left to the client (15). The MCP can fetch stored messages, so inbound mail can reach the model. The README's prompt-injection section asks users to review tool calls and goes no further (6). Logs API with 1 to 30 days of retention by plan, and Mailgun says security logs are kept 365 days (10). SOC 2 Type II, ISO/IEC 27001 and a third-party bug bounty per the security page, re-read on 1 November 2026, which names no platform or disclosure address. Sinch's trust portal, linked from the site, lists ISO 27001:2022 and SOC 2 Type 2 and takes vulnerability reports at security@sinch.com. No security.txt (404). Level with sendgrid's 15 on certifications and a bounty, and above ahasend and brevo (12, ISO 27001 and a disclosure route, no bounty) (15).

MailPace 50

Per-domain server tokens that can only send from and read status for their domain, and an organisation token that creates, renames and revokes domain tokens through the Domains API. Tokens travel in headers only. The authentication page still tells users to contact support to regenerate a leaked token (25 of 30). No read-only token. A domain token can't touch other domains, and the unpublished MCP server has an optional recipient allowlist. No approval step on the hosted API (8 of 20). Inbound mail reaches the customer's webhook as untrusted content, and Email Status returns bounce text. The MCP README warns about prompt injection and suggests the allowlist (9 of 15). The dashboard keeps sent mail for 30 days; no log of API calls was found (6 of 15). No security.txt (404 on mailpace.com and app.mailpace.com), no disclosure policy, bug bounty, SOC 2 or ISO 27001. WebAuthn-only two-factor sign-in and Ed25519-signed webhooks are documented (2 of 20). Total 50.

Mailgun API + MCP 87

Release notes on 29, 21, 20 and 13 October 2026 and mailgun-python 1.10.0 on 21 October (30). Release notes on 31 August, 1, 8, 15, 22 and 29 September and in October, mailgun.js 14.0.0 to 14.1.0 (12 August to 8 October) and mailgun-python 1.9.0 to 1.10.0 (4 August to 21 October), well over three in 90 days (20). The MCP repository merges pull requests and tags each release, the last v2.1.3 on 16 September. We couldn't see open issues or reply times from git (12). mailgun.js 14.1.0 (8 October) and mailgun-python 1.10.0 are current (15). MCP CI runs tests on Node 20, 22 and 24 plus lint, and npm releases publish from a workflow (10). 30 + 20 + 12 + 15 + 10 = 87.

MailPace 65

Email Status API documented on 22 October 2026, and the MCP server rewritten as 2.0.0 on 4 November 2026, two days before this check (30). In the 90 days from 8 August, the Q3 changelog post of 31 August, the Email Status docs of 22 October, a mailpace-rails push on 17 October and the MCP rewrite, but only one changelog post (15 of 20). A closed service with email support. Three pull requests to the MCP repository from 2025 have no reply (8 of 15). Not in the official MCP registry (search for mailpace returned nothing on 6 November). The Node library was last pushed in October 2024 and Go in January 2024, while mailpace-rails is current (7 of 15). The MCP server gained CI with tests on 4 November; the older SDKs weren't checked for CI (5 of 10). Total 65.

Mailgun API + MCP 40

No x402, MPP or L402 (0). Plan prices and per-1,000 overage ($1.80, $1.30, $1.10) published without login (20). Free plan of 100 emails a day with no card (20). A person signs up in a browser and verifies a domain, so no autonomous route (0).

MailPace 25

No x402, MPP or L402 (0). $10 a month for 10,000 emails and $1 per 1,000 after, loaded from Paddle on the pricing page and stated in the comparison pages' tables without login (20). A free plan of up to 100 emails a month is available only by emailing support, so it isn't self-serve (5 of 20). Signup, DKIM verification and payment happen in a browser (0). Total 25.

Mailgun API + MCP 60

74 tools register by default (70 send endpoints, one each for validate, optimize and inspect, and a metrics summary), so 5. --tags or MAILGUN_MCP_TAGS filters by product, but nearly everything is tagged send, so we add back 3 (8). Logs and analytics take limits, pagination and filters (18). The server turns API errors into messages that name the endpoint and the fix, and a 403 points at the billing page (16). No readOnlyHint or destructiveHint on any tool and no idempotency key for sends. o:testmode lets an agent check a send without delivery (4). Official Node and Python SDKs, and a send needs from, to, subject and a body (14).

MailPace 71

Responses are small, the send returns an id and status and Email Status returns one email (18 of 25). Only the domains list takes limit, offset, sort and direction; there is no endpoint to list or search sent mail (8 of 20). Errors are JSON with a human message and an HTTP status for each case in the documented table, with no stable error codes (14 of 20). Idempotency-Key on sends, kept 24 hours per token, and failed validations are not stored so they can be retried. The MCP server marks send as not idempotent and revoke as destructive (18 of 20). A send needs from, to, a subject and a body; official libraries for Node, Rails, Go and PHP transports and an SMTP route (13 of 15). Total 71.

Mailgun API + MCP 70

Closed service with published terms that name Sinch Email and the entity on the service order rather than one company. The MCP server is Apache-2.0 (18). Log retention by plan (1, 5 or 30 days) is on the pricing page, security logs 365 days, and a Sinch DPA is linked from the security page (22). Release notes date changes such as the May 2025 SMTP login change, and the MCP CHANGELOG flags its 2.0.0 tool renames, but we found no deprecation policy (12). Hosted on Google Cloud in US and EU regions. We didn't find a subprocessor list (12).

MailPace 75

Closed hosted service under terms that name OhMySMTP Ltd with its company number. The MCP server, SDKs, landing site and status page are MIT (18 of 30). The privacy policy (30 August 2026), the pricing page and the DPA agree on retention, 30 days in the dashboard and 7 more in backups, 37 days at most (25 of 30). The API reference promises an old version runs until a published end-of-life date, and the terms list dated changes. The terms also say changes apply immediately (8 of 20). Sub-processors listed with purpose and location, Freethought hosting in the EU, Hetzner backups in Germany, AppSignal in Amsterdam, Paddle in the UK and Tutanota in Germany (18 of 20). Total 69.