Postfix
Postfix is a free, open source mail transfer agent (MTA) originally written by Wietse Venema at IBM Research as a fast, secure, and easy-to-administer alternative to Sendmail. It runs on UNIX-like systems including Linux, BSD, and macOS, routing and delivering email over SMTP with extensive support for TLS, SASL, DKIM/SPF/DMARC integration, content filtering, and policy delegation. Postfix is administered via configuration files (main.cf, master.cf) and command-line tools rather than a public HTTP API, and is one of the most widely deployed mail servers on the internet.
Index entry only — little beyond a description and a link, and nothing machine-readable enough for an agent to act on without a human reading the site first.
API Evangelist profiles Postfix the way a machine reads it — 3 machine-readable artifacts across 1 API, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Postfix scores 11.1/100 (minimal), with a separate agent-readiness read of 0/100 (human only). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Postfix
Each block below is one kind of artifact we hold for Postfix. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 1
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
Postfix SMTP
Postfix implements SMTP (RFC 5321) for sending and receiving electronic mail, with submission (port 587), SMTPS (port 465), and standard SMTP (port 25) endpoints. There is no pu...
Security Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Every other property we hold for Postfix — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Documentation 1
Reference material describing how the API behaves
Build 1
SDKs, sample code, and the tooling you integrate with
Access & Security 3
Authentication, authorization, and security posture
Commercial 1
Pricing, plans, and the legal terms of use
Company 1
The organization behind the API
Other 3
Properties that don't map to a standard resource type
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