mirror of
https://github.com/docker-mailserver/docker-mailserver.git
synced 2024-01-19 02:48:50 +00:00
1873 lines
54 KiB
HTML
1873 lines
54 KiB
HTML
|
|
<!doctype html>
|
|
<html lang="en" class="no-js">
|
|
<head>
|
|
|
|
<meta charset="utf-8">
|
|
<meta name="viewport" content="width=device-width,initial-scale=1">
|
|
|
|
<meta name="description" content="A fullstack but simple mail-server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) using Docker.">
|
|
|
|
|
|
<meta name="author" content="docker-mailserver (Github Organization)">
|
|
|
|
|
|
<link rel="canonical" href="https://docker-mailserver.github.io/docker-mailserver/edge/config/security/understanding-the-ports/">
|
|
|
|
|
|
<link rel="prev" href="../../best-practices/autodiscover/">
|
|
|
|
|
|
<link rel="next" href="../ssl/">
|
|
|
|
<link rel="icon" href="../../../assets/logo/favicon-32x32.png">
|
|
<meta name="generator" content="mkdocs-1.4.2, mkdocs-material-9.1.5">
|
|
|
|
|
|
|
|
<title>Security | Understanding the Ports - Docker Mailserver</title>
|
|
|
|
|
|
|
|
<link rel="stylesheet" href="../../../assets/stylesheets/main.7a7fce14.min.css">
|
|
|
|
|
|
<link rel="stylesheet" href="../../../assets/stylesheets/palette.a0c5b2b5.min.css">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
|
|
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback">
|
|
<style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style>
|
|
|
|
|
|
|
|
<link rel="stylesheet" href="../../../assets/css/customizations.css">
|
|
|
|
<script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce((e,_)=>(e<<5)-e+_.charCodeAt(0),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</head>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<body dir="ltr" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo">
|
|
|
|
|
|
|
|
<script>var palette=__md_get("__palette");if(palette&&"object"==typeof palette.color)for(var key of Object.keys(palette.color))document.body.setAttribute("data-md-color-"+key,palette.color[key])</script>
|
|
|
|
<input class="md-toggle" data-md-toggle="drawer" type="checkbox" id="__drawer" autocomplete="off">
|
|
<input class="md-toggle" data-md-toggle="search" type="checkbox" id="__search" autocomplete="off">
|
|
<label class="md-overlay" for="__drawer"></label>
|
|
<div data-md-component="skip">
|
|
|
|
|
|
<a href="#quick-reference" class="md-skip">
|
|
Skip to content
|
|
</a>
|
|
|
|
</div>
|
|
<div data-md-component="announce">
|
|
|
|
</div>
|
|
|
|
<div data-md-color-scheme="default" data-md-component="outdated" hidden>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<header class="md-header" data-md-component="header">
|
|
<nav class="md-header__inner md-grid" aria-label="Header">
|
|
<a href="../../.." title="Docker Mailserver" class="md-header__button md-logo" aria-label="Docker Mailserver" data-md-component="logo">
|
|
|
|
<img src="../../../assets/logo/dmo-logo-white.min.svg" alt="logo">
|
|
|
|
</a>
|
|
<label class="md-header__button md-icon" for="__drawer">
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M3 6h18v2H3V6m0 5h18v2H3v-2m0 5h18v2H3v-2Z"/></svg>
|
|
</label>
|
|
<div class="md-header__title" data-md-component="header-title">
|
|
<div class="md-header__ellipsis">
|
|
<div class="md-header__topic">
|
|
<span class="md-ellipsis">
|
|
Docker Mailserver
|
|
</span>
|
|
</div>
|
|
<div class="md-header__topic" data-md-component="header-topic">
|
|
<span class="md-ellipsis">
|
|
|
|
Security | Understanding the Ports
|
|
|
|
</span>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
<form class="md-header__option" data-md-component="palette">
|
|
|
|
|
|
<input class="md-option" data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo" aria-label="Switch to dark mode" type="radio" name="__palette" id="__palette_1">
|
|
|
|
<label class="md-header__button md-icon" title="Switch to dark mode" for="__palette_2" hidden>
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="m17.75 4.09-2.53 1.94.91 3.06-2.63-1.81-2.63 1.81.91-3.06-2.53-1.94L12.44 4l1.06-3 1.06 3 3.19.09m3.5 6.91-1.64 1.25.59 1.98-1.7-1.17-1.7 1.17.59-1.98L15.75 11l2.06-.05L18.5 9l.69 1.95 2.06.05m-2.28 4.95c.83-.08 1.72 1.1 1.19 1.85-.32.45-.66.87-1.08 1.27C15.17 23 8.84 23 4.94 19.07c-3.91-3.9-3.91-10.24 0-14.14.4-.4.82-.76 1.27-1.08.75-.53 1.93.36 1.85 1.19-.27 2.86.69 5.83 2.89 8.02a9.96 9.96 0 0 0 8.02 2.89m-1.64 2.02a12.08 12.08 0 0 1-7.8-3.47c-2.17-2.19-3.33-5-3.49-7.82-2.81 3.14-2.7 7.96.31 10.98 3.02 3.01 7.84 3.12 10.98.31Z"/></svg>
|
|
</label>
|
|
|
|
|
|
|
|
<input class="md-option" data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme="slate" data-md-color-primary="indigo" data-md-color-accent="blue" aria-label="Switch to light mode" type="radio" name="__palette" id="__palette_2">
|
|
|
|
<label class="md-header__button md-icon" title="Switch to light mode" for="__palette_1" hidden>
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 7a5 5 0 0 1 5 5 5 5 0 0 1-5 5 5 5 0 0 1-5-5 5 5 0 0 1 5-5m0 2a3 3 0 0 0-3 3 3 3 0 0 0 3 3 3 3 0 0 0 3-3 3 3 0 0 0-3-3m0-7 2.39 3.42C13.65 5.15 12.84 5 12 5c-.84 0-1.65.15-2.39.42L12 2M3.34 7l4.16-.35A7.2 7.2 0 0 0 5.94 8.5c-.44.74-.69 1.5-.83 2.29L3.34 7m.02 10 1.76-3.77a7.131 7.131 0 0 0 2.38 4.14L3.36 17M20.65 7l-1.77 3.79a7.023 7.023 0 0 0-2.38-4.15l4.15.36m-.01 10-4.14.36c.59-.51 1.12-1.14 1.54-1.86.42-.73.69-1.5.83-2.29L20.64 17M12 22l-2.41-3.44c.74.27 1.55.44 2.41.44.82 0 1.63-.17 2.37-.44L12 22Z"/></svg>
|
|
</label>
|
|
|
|
|
|
</form>
|
|
|
|
|
|
|
|
<label class="md-header__button md-icon" for="__search">
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.516 6.516 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5Z"/></svg>
|
|
</label>
|
|
<div class="md-search" data-md-component="search" role="dialog">
|
|
<label class="md-search__overlay" for="__search"></label>
|
|
<div class="md-search__inner" role="search">
|
|
<form class="md-search__form" name="search">
|
|
<input type="text" class="md-search__input" name="query" aria-label="Search" placeholder="Search" autocapitalize="off" autocorrect="off" autocomplete="off" spellcheck="false" data-md-component="search-query" required>
|
|
<label class="md-search__icon md-icon" for="__search">
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.516 6.516 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5Z"/></svg>
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11h12Z"/></svg>
|
|
</label>
|
|
<nav class="md-search__options" aria-label="Search">
|
|
|
|
<button type="reset" class="md-search__icon md-icon" title="Clear" aria-label="Clear" tabindex="-1">
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M19 6.41 17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12 19 6.41Z"/></svg>
|
|
</button>
|
|
</nav>
|
|
|
|
</form>
|
|
<div class="md-search__output">
|
|
<div class="md-search__scrollwrap" data-md-scrollfix>
|
|
<div class="md-search-result" data-md-component="search-result">
|
|
<div class="md-search-result__meta">
|
|
Initializing search
|
|
</div>
|
|
<ol class="md-search-result__list" role="presentation"></ol>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<div class="md-header__source">
|
|
<a href="https://github.com/docker-mailserver/docker-mailserver" title="Go to repository" class="md-source" data-md-component="source">
|
|
<div class="md-source__icon md-icon">
|
|
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 496 512"><!--! Font Awesome Free 6.3.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2023 Fonticons, Inc.--><path d="M165.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6zm-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3zm44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9zM244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8zM97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1zm-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7zm32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1zm-11.4-14.7c-1.6 1-1.6 3.6 0 5.9 1.6 2.3 4.3 3.3 5.6 2.3 1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2z"/></svg>
|
|
</div>
|
|
<div class="md-source__repository">
|
|
docker-mailserver
|
|
</div>
|
|
</a>
|
|
</div>
|
|
|
|
</nav>
|
|
|
|
</header>
|
|
|
|
<div class="md-container" data-md-component="container">
|
|
|
|
|
|
|
|
|
|
|
|
<nav class="md-tabs" aria-label="Tabs" data-md-component="tabs">
|
|
<div class="md-grid">
|
|
<ul class="md-tabs__list">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../.." class="md-tabs__link">
|
|
Home
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../../introduction/" class="md-tabs__link">
|
|
Introduction
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../../usage/" class="md-tabs__link">
|
|
Usage
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../environment/" class="md-tabs__link md-tabs__link--active">
|
|
Configuration
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../../examples/tutorials/basic-installation/" class="md-tabs__link">
|
|
Examples
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../../faq/" class="md-tabs__link">
|
|
FAQ
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="../../../contributing/general/" class="md-tabs__link">
|
|
Contributing
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="https://hub.docker.com/r/mailserver/docker-mailserver/" class="md-tabs__link">
|
|
DockerHub
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-tabs__item">
|
|
<a href="https://github.com/docker-mailserver/docker-mailserver/pkgs/container/docker-mailserver" class="md-tabs__link">
|
|
GHCR
|
|
</a>
|
|
</li>
|
|
|
|
|
|
</ul>
|
|
</div>
|
|
</nav>
|
|
|
|
|
|
|
|
<main class="md-main" data-md-component="main">
|
|
<div class="md-main__inner md-grid">
|
|
|
|
|
|
|
|
<div class="md-sidebar md-sidebar--primary" data-md-component="sidebar" data-md-type="navigation" >
|
|
<div class="md-sidebar__scrollwrap">
|
|
<div class="md-sidebar__inner">
|
|
|
|
|
|
|
|
|
|
|
|
<nav class="md-nav md-nav--primary md-nav--lifted" aria-label="Navigation" data-md-level="0">
|
|
<label class="md-nav__title" for="__drawer">
|
|
<a href="../../.." title="Docker Mailserver" class="md-nav__button md-logo" aria-label="Docker Mailserver" data-md-component="logo">
|
|
|
|
<img src="../../../assets/logo/dmo-logo-white.min.svg" alt="logo">
|
|
|
|
</a>
|
|
Docker Mailserver
|
|
</label>
|
|
|
|
<div class="md-nav__source">
|
|
<a href="https://github.com/docker-mailserver/docker-mailserver" title="Go to repository" class="md-source" data-md-component="source">
|
|
<div class="md-source__icon md-icon">
|
|
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 496 512"><!--! Font Awesome Free 6.3.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2023 Fonticons, Inc.--><path d="M165.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6zm-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3zm44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9zM244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8zM97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1zm-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7zm32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1zm-11.4-14.7c-1.6 1-1.6 3.6 0 5.9 1.6 2.3 4.3 3.3 5.6 2.3 1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2z"/></svg>
|
|
</div>
|
|
<div class="md-source__repository">
|
|
docker-mailserver
|
|
</div>
|
|
</a>
|
|
</div>
|
|
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../.." class="md-nav__link">
|
|
Home
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../introduction/" class="md-nav__link">
|
|
Introduction
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../usage/" class="md-nav__link">
|
|
Usage
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--active md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" checked>
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="0">
|
|
Configuration
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="true">
|
|
<label class="md-nav__title" for="__nav_4">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Configuration
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../environment/" class="md-nav__link">
|
|
Environment Variables
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../user-management/" class="md-nav__link">
|
|
User Management
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_4_3" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4_3" id="__nav_4_3_label" tabindex="0">
|
|
Best Practices
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_3_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_4_3">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Best Practices
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../best-practices/dkim_dmarc_spf/" class="md-nav__link">
|
|
DKIM, DMARC & SPF
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../best-practices/autodiscover/" class="md-nav__link">
|
|
Auto-discovery
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--active md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_4" checked>
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4_4" id="__nav_4_4_label" tabindex="0">
|
|
Security
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_4_label" aria-expanded="true">
|
|
<label class="md-nav__title" for="__nav_4_4">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Security
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--active">
|
|
|
|
<input class="md-nav__toggle md-toggle" type="checkbox" id="__toc">
|
|
|
|
|
|
|
|
<label class="md-nav__link md-nav__link--active" for="__toc">
|
|
Understanding the Ports
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<a href="./" class="md-nav__link md-nav__link--active">
|
|
Understanding the Ports
|
|
</a>
|
|
|
|
|
|
|
|
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
|
|
|
|
|
|
|
|
|
|
<label class="md-nav__title" for="__toc">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Table of contents
|
|
</label>
|
|
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#quick-reference" class="md-nav__link">
|
|
Quick Reference
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#overview-of-email-ports" class="md-nav__link">
|
|
Overview of Email Ports
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="Overview of Email Ports">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#what-ports-should-i-use-smtp" class="md-nav__link">
|
|
What Ports Should I Use? (SMTP)
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="What Ports Should I Use? (SMTP)">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#inbound-traffic-on-the-left" class="md-nav__link">
|
|
Inbound Traffic (On the left)
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#outbound-traffic-on-the-right" class="md-nav__link">
|
|
Outbound Traffic (On the Right)
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#explicit-vs-implicit-tls" class="md-nav__link">
|
|
Explicit vs Implicit TLS
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="Explicit vs Implicit TLS">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#explicit-tls-aka-opportunistic-tls-opt-in-encryption" class="md-nav__link">
|
|
Explicit TLS (aka Opportunistic TLS) - Opt-in Encryption
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#implicit-tls-enforced-encryption" class="md-nav__link">
|
|
Implicit TLS - Enforced Encryption
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#security" class="md-nav__link">
|
|
Security
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="Security">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#tls-connections-for-a-mail-server-compared-to-web-browsers" class="md-nav__link">
|
|
TLS connections for a Mail Server, compared to web browsers
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../ssl/" class="md-nav__link">
|
|
SSL/TLS
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../fail2ban/" class="md-nav__link">
|
|
Fail2Ban
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../mail_crypt/" class="md-nav__link">
|
|
Mail Encryption
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../rspamd/" class="md-nav__link">
|
|
Rspamd
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../debugging/" class="md-nav__link">
|
|
Debugging
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../pop3/" class="md-nav__link">
|
|
Mail Delivery with POP3
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../setup.sh/" class="md-nav__link">
|
|
About setup.sh
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_4_8" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4_8" id="__nav_4_8_label" tabindex="0">
|
|
Advanced Configuration
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_8_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_4_8">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Advanced Configuration
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/optional-config/" class="md-nav__link">
|
|
Optional Configuration
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_4_8_2" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4_8_2" id="__nav_4_8_2_label" tabindex="0">
|
|
Maintenance
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_8_2_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_4_8_2">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Maintenance
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/maintenance/update-and-cleanup/" class="md-nav__link">
|
|
Update and Cleanup
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_4_8_3" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4_8_3" id="__nav_4_8_3_label" tabindex="0">
|
|
Override the Default Configs
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_8_3_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_4_8_3">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Override the Default Configs
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/override-defaults/dovecot/" class="md-nav__link">
|
|
Dovecot
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/override-defaults/postfix/" class="md-nav__link">
|
|
Postfix
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/override-defaults/user-patches/" class="md-nav__link">
|
|
Modifications via Script
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/auth-ldap/" class="md-nav__link">
|
|
LDAP Authentication
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/mail-sieve/" class="md-nav__link">
|
|
Email Filtering with Sieve
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/mail-fetchmail/" class="md-nav__link">
|
|
Email Gathering with Fetchmail
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/mail-getmail/" class="md-nav__link">
|
|
Email Gathering with Getmail
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_4_8_8" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_4_8_8" id="__nav_4_8_8_label" tabindex="0">
|
|
Email Forwarding
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_8_8_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_4_8_8">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Email Forwarding
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/mail-forwarding/relay-hosts/" class="md-nav__link">
|
|
Relay Hosts
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/mail-forwarding/aws-ses/" class="md-nav__link">
|
|
AWS SES
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/full-text-search/" class="md-nav__link">
|
|
Full-Text Search
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/kubernetes/" class="md-nav__link">
|
|
Kubernetes
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/ipv6/" class="md-nav__link">
|
|
IPv6
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/podman/" class="md-nav__link">
|
|
Podman
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../advanced/dovecot-master-accounts/" class="md-nav__link">
|
|
Dovecot Master Accounts
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_5" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_5" id="__nav_5_label" tabindex="0">
|
|
Examples
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_5_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_5">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Examples
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_5_1" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_5_1" id="__nav_5_1_label" tabindex="0">
|
|
Tutorials
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_5_1_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_5_1">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Tutorials
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../examples/tutorials/basic-installation/" class="md-nav__link">
|
|
Basic Installation
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../examples/tutorials/mailserver-behind-proxy/" class="md-nav__link">
|
|
Mailserver behind Proxy
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../examples/tutorials/docker-build/" class="md-nav__link">
|
|
Building your own Docker image
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../examples/tutorials/blog-posts/" class="md-nav__link">
|
|
Blog Posts
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_5_2" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_5_2" id="__nav_5_2_label" tabindex="0">
|
|
Use Cases
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_5_2_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_5_2">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Use Cases
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../examples/use-cases/forward-only-mailserver-with-ldap-authentication/" class="md-nav__link">
|
|
Forward-Only Mail-Server with LDAP
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../examples/use-cases/imap-folders/" class="md-nav__link">
|
|
Customize IMAP Folders
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../faq/" class="md-nav__link">
|
|
FAQ
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item md-nav__item--nested">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<input class="md-nav__toggle md-toggle md-toggle--indeterminate" type="checkbox" id="__nav_7" >
|
|
|
|
|
|
|
|
<label class="md-nav__link" for="__nav_7" id="__nav_7_label" tabindex="0">
|
|
Contributing
|
|
<span class="md-nav__icon md-icon"></span>
|
|
</label>
|
|
|
|
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_7_label" aria-expanded="false">
|
|
<label class="md-nav__title" for="__nav_7">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Contributing
|
|
</label>
|
|
<ul class="md-nav__list" data-md-scrollfix>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../contributing/general/" class="md-nav__link">
|
|
General Information
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../contributing/tests/" class="md-nav__link">
|
|
Tests
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="../../../contributing/issues-and-pull-requests/" class="md-nav__link">
|
|
Issues and Pull Requests
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="https://hub.docker.com/r/mailserver/docker-mailserver/" class="md-nav__link">
|
|
DockerHub
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<li class="md-nav__item">
|
|
<a href="https://github.com/docker-mailserver/docker-mailserver/pkgs/container/docker-mailserver" class="md-nav__link">
|
|
GHCR
|
|
</a>
|
|
</li>
|
|
|
|
|
|
|
|
</ul>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
|
|
<div class="md-sidebar md-sidebar--secondary" data-md-component="sidebar" data-md-type="toc" >
|
|
<div class="md-sidebar__scrollwrap">
|
|
<div class="md-sidebar__inner">
|
|
|
|
|
|
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
|
|
|
|
|
|
|
|
|
|
<label class="md-nav__title" for="__toc">
|
|
<span class="md-nav__icon md-icon"></span>
|
|
Table of contents
|
|
</label>
|
|
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#quick-reference" class="md-nav__link">
|
|
Quick Reference
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#overview-of-email-ports" class="md-nav__link">
|
|
Overview of Email Ports
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="Overview of Email Ports">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#what-ports-should-i-use-smtp" class="md-nav__link">
|
|
What Ports Should I Use? (SMTP)
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="What Ports Should I Use? (SMTP)">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#inbound-traffic-on-the-left" class="md-nav__link">
|
|
Inbound Traffic (On the left)
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#outbound-traffic-on-the-right" class="md-nav__link">
|
|
Outbound Traffic (On the Right)
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#explicit-vs-implicit-tls" class="md-nav__link">
|
|
Explicit vs Implicit TLS
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="Explicit vs Implicit TLS">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#explicit-tls-aka-opportunistic-tls-opt-in-encryption" class="md-nav__link">
|
|
Explicit TLS (aka Opportunistic TLS) - Opt-in Encryption
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#implicit-tls-enforced-encryption" class="md-nav__link">
|
|
Implicit TLS - Enforced Encryption
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#security" class="md-nav__link">
|
|
Security
|
|
</a>
|
|
|
|
<nav class="md-nav" aria-label="Security">
|
|
<ul class="md-nav__list">
|
|
|
|
<li class="md-nav__item">
|
|
<a href="#tls-connections-for-a-mail-server-compared-to-web-browsers" class="md-nav__link">
|
|
TLS connections for a Mail Server, compared to web browsers
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</nav>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
|
|
<div class="md-content" data-md-component="content">
|
|
<article class="md-content__inner md-typeset">
|
|
|
|
|
|
|
|
|
|
<a href="https://github.com/docker-mailserver/docker-mailserver/edit/master/docs/content/config/security/understanding-the-ports.md" title="Edit this page" class="md-content__button md-icon">
|
|
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M10 20H6V4h7v5h5v3.1l2-2V8l-6-6H6c-1.1 0-2 .9-2 2v16c0 1.1.9 2 2 2h4v-2m10.2-7c.1 0 .3.1.4.2l1.3 1.3c.2.2.2.6 0 .8l-1 1-2.1-2.1 1-1c.1-.1.2-.2.4-.2m0 3.9L14.1 23H12v-2.1l6.1-6.1 2.1 2.1Z"/></svg>
|
|
</a>
|
|
|
|
|
|
|
|
|
|
|
|
<a href="https://github.com/docker-mailserver/docker-mailserver/raw/master/docs/content/config/security/understanding-the-ports.md" title="View source of this page" class="md-content__button md-icon">
|
|
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M17 18c.56 0 1 .44 1 1s-.44 1-1 1-1-.44-1-1 .44-1 1-1m0-3c-2.73 0-5.06 1.66-6 4 .94 2.34 3.27 4 6 4s5.06-1.66 6-4c-.94-2.34-3.27-4-6-4m0 6.5a2.5 2.5 0 0 1-2.5-2.5 2.5 2.5 0 0 1 2.5-2.5 2.5 2.5 0 0 1 2.5 2.5 2.5 2.5 0 0 1-2.5 2.5M9.27 20H6V4h7v5h5v4.07c.7.08 1.36.25 2 .49V8l-6-6H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h4.5a8.15 8.15 0 0 1-1.23-2Z"/></svg>
|
|
</a>
|
|
|
|
|
|
|
|
<h1>Understanding the Ports</h1>
|
|
|
|
<h2 id="quick-reference"><a class="toclink" href="#quick-reference">Quick Reference</a></h2>
|
|
<p>Prefer ports with Implicit <a href="https://en.wikipedia.org/wiki/Transport_Layer_Security">TLS</a> ports, they're more secure than ports using Explicit TLS, and if you use a Reverse Proxy should be less hassle.</p>
|
|
<h2 id="overview-of-email-ports"><a class="toclink" href="#overview-of-email-ports">Overview of Email Ports</a></h2>
|
|
<table>
|
|
<thead>
|
|
<tr>
|
|
<th>Protocol</th>
|
|
<th>Explicit TLS<sup>1</sup></th>
|
|
<th>Implicit TLS</th>
|
|
<th>Purpose</th>
|
|
<th>Enabled by Default</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<td><a href="https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol#Modern_SMTP">ESMTP</a></td>
|
|
<td>25</td>
|
|
<td>N/A</td>
|
|
<td>Transfer<sup>2</sup></td>
|
|
<td>Yes</td>
|
|
</tr>
|
|
<tr>
|
|
<td>ESMTP</td>
|
|
<td>587</td>
|
|
<td>465<sup>3</sup></td>
|
|
<td>Submission</td>
|
|
<td>Yes</td>
|
|
</tr>
|
|
<tr>
|
|
<td>POP3</td>
|
|
<td>110</td>
|
|
<td>995</td>
|
|
<td>Retrieval</td>
|
|
<td>No</td>
|
|
</tr>
|
|
<tr>
|
|
<td>IMAP4</td>
|
|
<td>143</td>
|
|
<td>993</td>
|
|
<td>Retrieval</td>
|
|
<td>Yes</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<ol>
|
|
<li>A connection <em>may</em> be secured over TLS when both ends support <code>STARTTLS</code>. On ports 110, 143 and 587, DMS will reject a connection that cannot be secured. Port 25 is <a href="https://serverfault.com/questions/623692/is-it-still-wrong-to-require-starttls-on-incoming-smtp-messages">required</a> to support insecure connections.</li>
|
|
<li>Receives email, DMS additionally filters for spam and viruses. For submitting email to the server to be sent to third-parties, you should prefer the <em>submission</em> ports (465, 587) - which require authentication. Unless a relay host is configured (eg: SendGrid), outgoing email will leave the server via port 25 (<em>thus outbound traffic must not be blocked by your provider or firewall</em>).</li>
|
|
<li>A <em>submission</em> port since 2018 (<a href="https://tools.ietf.org/html/rfc8314">RFC 8314</a>).</li>
|
|
</ol>
|
|
<details class="warning">
|
|
<summary>Beware of outdated advice on port 465</summary>
|
|
<p>There is a common misconception of this port due to it's history detailed by various communities and blogs articles on the topic (<em>including by popular mail relay services</em>).</p>
|
|
<p>Port 465 was <a href="https://en.wikipedia.org/wiki/SMTPS#History">briefly assigned the role of SMTPS in 1997</a> as an secure alternative to Port 25 between MTA exchanges. Then RFC 2487 (<code>STARTTLS</code>) <a href="https://web.archive.org/web/20150603202057/http://www.imc.org/ietf-apps-tls/mail-archive/msg00204.html">while still in a draft status in late 1998 had IANA revoke the SMTPS assignment</a>. The <a href="https://mailing.postfix.users.narkive.com/F3ACwg2F/which-port-to-use-for-ssl-tls#post21">draft history was modified to exclude all mention of port 465 and SMTPS</a>.</p>
|
|
<p>In 2018 <a href="https://tools.ietf.org/html/rfc8314">RFC 8314</a> was published which revives Port 465 as an Implicit TLS alternative to Port 587 for mail submission. It details very clearly that gaining adoption of 465 as the preferred port will take time. IANA reassigned <a href="https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=465">port 465 as the <code>submissions</code> service</a>. Any unofficial usage as <strong>SMTPS is legacy and has been for over two decades</strong>.</p>
|
|
<p>Understand that port 587 is more broadly supported due to this history and that lots of software in that time has been built or configured with that port in mind. <a href="https://blog.apnic.net/2021/11/18/vulnerabilities-show-why-starttls-should-be-avoided-if-possible/"><code>STARTTLS</code> is known to have various CVEs discovered even in recent years</a>, do not be misled by any advice implying it should be preferred over implicit TLS. Trust in more official sources, such as the <a href="https://github.com/vdukhovni/postfix/blob/62931e5b1f9f1e80d02a496c7fd0062a5aae1d25/postfix/conf/master.cf#L38-L41">config Postfix has</a> which acknowledges the <code>submissions</code> port (465).</p>
|
|
</details>
|
|
<h3 id="what-ports-should-i-use-smtp"><a class="toclink" href="#what-ports-should-i-use-smtp">What Ports Should I Use? (SMTP)</a></h3>
|
|
<pre class="mermaid"><code>flowchart LR
|
|
subgraph your-server ["Your Server"]
|
|
in_25(25) --> server
|
|
in_465(465) --> server
|
|
server(("docker-mailserver<br/>hello@world.com"))
|
|
server --- out_25(25)
|
|
server --- out_465(465)
|
|
end
|
|
|
|
third-party("Third-party<br/>(sending you email)") ---|"Receive email for<br/>hello@world.com"| in_25
|
|
|
|
subgraph clients ["Clients (MUA)"]
|
|
mua-client(Thunderbird,<br/>Webmail,<br/>Mutt,<br/>etc)
|
|
mua-service(Backend software<br/>on another server)
|
|
end
|
|
clients ---|"Send email as<br/>hello@world.com"| in_465
|
|
|
|
out_25(25) -->|"Direct<br/>Delivery"| tin_25
|
|
out_465(465) --> relay("MTA<br/>Relay Server") --> tin_25(25)
|
|
|
|
subgraph third-party-server["Third-party Server"]
|
|
third-party-mta("MTA<br/>friend@example.com")
|
|
tin_25(25) --> third-party-mta
|
|
end</code></pre>
|
|
<hr />
|
|
<h4 id="inbound-traffic-on-the-left"><a class="toclink" href="#inbound-traffic-on-the-left">Inbound Traffic (On the left)</a></h4>
|
|
<p>Mail arriving at your server will be processed and stored in a mailbox, or sent outbound to another mail server.</p>
|
|
<ul>
|
|
<li><strong>Port 25:</strong><ul>
|
|
<li>Think of this like a physical mailbox, anyone can deliver mail to you here. Typically most mail is delivered to you on this port.</li>
|
|
<li>DMS will actively filter email delivered on this port for spam or viruses, and refuse mail from known bad sources.</li>
|
|
<li>Connections to this port may be secure through STARTTLS, but is not mandatory as <a href="https://serverfault.com/questions/623692/is-it-still-wrong-to-require-starttls-on-incoming-smtp-messages">mail is allowed to arrive via an unencrypted connection</a>.</li>
|
|
<li>It is possible for internal clients to submit mail to be sent outbound (<em>without requiring authentication</em>), but that is discouraged. Prefer the <em>submission</em> ports.</li>
|
|
</ul>
|
|
</li>
|
|
<li><strong>Port 465 and 587:</strong><ul>
|
|
<li>This is the equivalent of a post office box where you would send email to be delivered on your behalf (<em>DMS is that metaphorical post office, aka the MTA</em>).</li>
|
|
<li>These two ports are known as the <em>submission</em> ports, they enable mail to be sent outbound to another MTA (eg: Outlook or Gmail) but require authentication via a <a href="../../user-management/#accounts">mail account</a>.</li>
|
|
<li>For inbound traffic, this is relevant when you send mail from your MUA (eg: ThunderBird). It's also used when DMS is configured as a mail relay, or when you have a service sending transactional mail (<em>eg: order confirmations, password resets, notifications</em>) through DMS.</li>
|
|
<li><em><strong>Prefer port 465</strong></em> over port 587, as 465 provides Implicit TLS.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>When submitting mail (inbound) to be sent (outbound), this involves two separate connections to negotiate and secure. There may be additional intermediary connections which DMS is not involved in, and thus unable to ensure encrypted transit throughout delivery.</p>
|
|
</div>
|
|
<h4 id="outbound-traffic-on-the-right"><a class="toclink" href="#outbound-traffic-on-the-right">Outbound Traffic (On the Right)</a></h4>
|
|
<p>Mail being sent from your server is either being relayed through another MTA (eg: SendGrid), or direct to an MTA responsible for an email address (eg: Gmail).</p>
|
|
<ul>
|
|
<li><strong>Port 25:</strong><ul>
|
|
<li>As most MTA use port 25 to receive inbound mail, when no authenticated relay is involved this is the outbound port used.</li>
|
|
<li>Outbound traffic on this port is often blocked by service providers (eg: VPS, ISP) to prevent abuse by spammers. If the port cannot be unblocked, you will need to relay outbound mail through a service to send on your behalf.</li>
|
|
</ul>
|
|
</li>
|
|
<li><strong>Port 465 and 587:</strong><ul>
|
|
<li>Submission ports for outbound traffic establish trust to forward mail through a third-party relay service. This requires <a href="../../advanced/mail-forwarding/relay-hosts/">authenticating to an account on the relay service</a>. The relay will then deliver the mail through port 25 on your behalf.</li>
|
|
<li>These are the two typical ports used, but smart hosts like SendGrid often document support for additional non-standard ports as alternatives if necessary.</li>
|
|
<li>Usually you'll only use these outbound ports for relaying. It is possible to deliver directly to the relevant MTA for email address, but requires having credentials for each MTA.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<div class="admonition tip">
|
|
<p class="admonition-title">Tip</p>
|
|
<p>DMS can function as a relay too, but professional relay services have a trusted reputation (<em>which increases success of delivery</em>).</p>
|
|
<p>An MTA with low reputation can affect if mail is treated as junk, or even rejected.</p>
|
|
</div>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>At best, you can only ensure a secure connection between the MTA you directly connect to. The receiving MTA may relay that mail to another MTA (<em>and so forth</em>), each connection may not be enforcing TLS.</p>
|
|
</div>
|
|
<h3 id="explicit-vs-implicit-tls"><a class="toclink" href="#explicit-vs-implicit-tls">Explicit vs Implicit TLS</a></h3>
|
|
<h4 id="explicit-tls-aka-opportunistic-tls-opt-in-encryption"><a class="toclink" href="#explicit-tls-aka-opportunistic-tls-opt-in-encryption">Explicit TLS (aka Opportunistic TLS) - Opt-in Encryption</a></h4>
|
|
<p>Communication on these ports begin in <a href="https://www.denimgroup.com/resources/blog/2007/10/cleartext-vs-pl">cleartext</a>. Upgrading to an encrypted connection must be requested explicitly through the <code>STARTTLS</code> protocol <strong>and</strong> successfully negotiated.</p>
|
|
<p>Sometimes a reverse-proxy is involved, but is misconfigured or lacks support for the <code>STARTTLS</code> negotiation to succeed.</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<ul>
|
|
<li>By default, DMS is configured to reject connections that fail to establish a secure connection (<em>when authentication is required</em>), rather than allow an insecure connection.</li>
|
|
<li>Port 25 does not require authentication. If <code>STARTTLS</code> is unsuccessful, mail can be received over an unencrypted connection. You can better secure this port between trusted parties with the addition of MTA-STS, <a href="https://github.com/EFForg/starttls-everywhere#email-security-database-starttls-policy-list">STARTTLS Policy List</a>, DNSSEC and DANE.</li>
|
|
</ul>
|
|
</div>
|
|
<div class="admonition warning">
|
|
<p class="admonition-title">Warning</p>
|
|
<p><code>STARTTLS</code> <a href="https://blog.apnic.net/2021/11/18/vulnerabilities-show-why-starttls-should-be-avoided-if-possible/">continues to have vulnerabilities found</a> (Nov 2021 article), as per <a href="https://tools.ietf.org/html/rfc8314#section-4.1">RFC 8314 (Section 4.1)</a> you are encouraged to <strong>prefer Implicit TLS where possible</strong>.</p>
|
|
<p>Support for <code>STARTTLS</code> is not always implemented correctly, which can lead to leaking credentials (like a client sending too early) prior to a TLS connection being established. Third-parties such as some ISPs have also been known to intercept the <code>STARTTLS</code> exchange, modifying network traffic to prevent establishing a secure connection.</p>
|
|
</div>
|
|
<h4 id="implicit-tls-enforced-encryption"><a class="toclink" href="#implicit-tls-enforced-encryption">Implicit TLS - Enforced Encryption</a></h4>
|
|
<p>Communication on these ports are always encrypted (<em>enforced, thus implicit</em>), avoiding the potential risks with <code>STARTTLS</code> (Explicit TLS).</p>
|
|
<p>While Explicit TLS can provide the same benefit (<em>when <code>STARTTLS</code> is successfully negotiated</em>), Implicit TLS more reliably avoids concerns with connection manipulation and compatibility.</p>
|
|
<h2 id="security"><a class="toclink" href="#security">Security</a></h2>
|
|
<div class="admonition todo">
|
|
<p class="admonition-title">Todo</p>
|
|
<p>This section should provide any related configuration advice, and probably expand on and link to resources about DANE, DNSSEC, MTA-STS and STARTTLS Policy list, with advice on how to configure/setup these added security layers.</p>
|
|
</div>
|
|
<div class="admonition todo">
|
|
<p class="admonition-title">Todo</p>
|
|
<p>A related section or page on ciphers used may be useful, although less important for users to be concerned about.</p>
|
|
</div>
|
|
<h3 id="tls-connections-for-a-mail-server-compared-to-web-browsers"><a class="toclink" href="#tls-connections-for-a-mail-server-compared-to-web-browsers">TLS connections for a Mail Server, compared to web browsers</a></h3>
|
|
<p>Unlike with HTTP where a web browser client communicates directly with the server providing a website, a secure TLS connection as discussed below does not provide the equivalent safety that HTTPS does when the transit of email (receiving or sending) is sent through third-parties, as the secure connection is only between two machines, any additional machines (MTAs) between the MUA and the MDA depends on them establishing secure connections between one another successfully.</p>
|
|
<p>Other machines that facilitate a connection that generally aren't taken into account can exist between a client and server, such as those where your connection passes through your ISP provider are capable of compromising a <code>cleartext</code> connection through interception.</p>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</article>
|
|
</div>
|
|
|
|
|
|
</div>
|
|
|
|
<button type="button" class="md-top md-icon" data-md-component="top" hidden>
|
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8v12Z"/></svg>
|
|
Back to top
|
|
</button>
|
|
|
|
</main>
|
|
|
|
<footer class="md-footer">
|
|
|
|
<div class="md-footer-meta md-typeset">
|
|
<div class="md-footer-meta__inner md-grid">
|
|
<div class="md-copyright">
|
|
|
|
<div class="md-copyright__highlight">
|
|
<p>© <a href="https://github.com/docker-mailserver"><em>Docker Mailserver Organization</em></a><br/><span>This project is licensed under the MIT license.</span></p>
|
|
</div>
|
|
|
|
|
|
Made with
|
|
<a href="https://squidfunk.github.io/mkdocs-material/" target="_blank" rel="noopener">
|
|
Material for MkDocs
|
|
</a>
|
|
|
|
</div>
|
|
|
|
</div>
|
|
</div>
|
|
</footer>
|
|
|
|
</div>
|
|
<div class="md-dialog" data-md-component="dialog">
|
|
<div class="md-dialog__inner md-typeset"></div>
|
|
</div>
|
|
|
|
<script id="__config" type="application/json">{"base": "../../..", "features": ["navigation.tabs", "navigation.top", "navigation.expand", "navigation.instant", "content.action.edit", "content.action.view", "content.code.annotate"], "search": "../../../assets/javascripts/workers/search.208ed371.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}, "version": {"provider": "mike"}}</script>
|
|
|
|
|
|
<script src="../../../assets/javascripts/bundle.407015b8.min.js"></script>
|
|
|
|
|
|
</body>
|
|
</html> |