aid: postfix
name: Postfix
description: >-
  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.
type: Index
image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
tags:
  - Email
  - Mail Server
  - MTA
  - SMTP
  - Open Source
  - Infrastructure
url: >-
  https://raw.githubusercontent.com/api-evangelist/postfix/refs/heads/main/apis.yml
created: '2026-05-11'
modified: '2026-05-11'
specificationVersion: '0.19'
apis:
  - aid: postfix:smtp
    name: Postfix SMTP
    description: >-
      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 public HTTP/REST API; integration is
      via SMTP protocol, configuration files, milter (mail filter) hooks, and
      policy daemons.
    humanURL: https://www.postfix.org/documentation.html
    baseURL: smtp://localhost:25
    tags:
      - SMTP
      - Email
      - Mail Server
      - Protocol
    properties:
      - type: Documentation
        url: https://www.postfix.org/documentation.html
      - type: SMTP Specification
        url: https://datatracker.ietf.org/doc/html/rfc5321
      - type: Configuration Reference
        url: https://www.postfix.org/postconf.5.html
      - type: Milter Protocol
        url: https://www.postfix.org/MILTER_README.html

common:
  - type: Website
    url: https://www.postfix.org
  - type: Documentation
    url: https://www.postfix.org/documentation.html
  - type: Download
    url: https://www.postfix.org/download.html
  - type: Source Code
    url: https://github.com/vdukhovni/postfix
  - type: Mailing Lists
    url: https://www.postfix.org/lists.html
  - type: Security
    url: https://www.postfix.org/security.html
  - type: License
    url: https://www.postfix.org/license.html
  - type: Wikipedia
    url: https://en.wikipedia.org/wiki/Postfix_(software)
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com