github-com-docker-mailserver/docker-mailserver
1
0
Fork 0
mirror of https://github.com/docker-mailserver/docker-mailserver.git synced 2024-01-19 02:48:50 +00:00
Code Issues Projects Releases Wiki Activity
docker-mailserver/edge/config/best-practices/dkim/index.html
github-actions[bot] 1b978c9912 deploy: cf22475382
2021-05-20 10:25:17 +00:00

1513 lines
43 KiB
HTML
Raw Blame History

<!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/best-practices/dkim/">
<link rel="icon" href="../../../assets/logo/favicon-32x32.png">
<meta name="generator" content="mkdocs-1.1.2, mkdocs-material-7.1.4">
<title>Best Practices | DKIM - Docker Mailserver</title>
<link rel="stylesheet" href="../../../assets/stylesheets/main.bde7dde4.min.css">
<link rel="stylesheet" href="../../../assets/stylesheets/palette.ef6f36e2.min.css">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,400,400i,700%7CRoboto+Mono&display=fallback">
<style>:root{--md-text-font-family:"Roboto";--md-code-font-family:"Roboto Mono"}</style>
<link rel="stylesheet" href="../../../assets/css/customizations.css">
</head>
<body dir="ltr" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo">
<script>function __prefix(e){return new URL("../../..",location).pathname+"."+e}function __get(e,t=localStorage){return JSON.parse(t.getItem(__prefix(e)))}</script>
<script>var palette=__get("__palette");if(null!==palette&&"object"==typeof palette.color)for(var key in 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="#enabling-dkim-signature" class="md-skip">
Skip to content
</a>
</div>
<div data-md-component="announce">
</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">
Best Practices | DKIM
</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" 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" 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" data-md-state="active" 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>
<button type="reset" class="md-search__icon md-icon" 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>
</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"></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"><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-tabs__inner 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="../../setup.sh/" 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/issues-and-pull-requests/" class="md-tabs__link">
Contributing
</a>
</li>
<li class="md-tabs__item">
<a href="https://hub.docker.com/repository/docker/mailserver/docker-mailserver" class="md-tabs__link">
DockerHub
</a>
</li>
<li class="md-tabs__item">
<a href="https://github.com/orgs/docker-mailserver/packages/container/package/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"><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 md-nav__item--active md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_3" type="checkbox" id="__nav_3" checked>
<label class="md-nav__link" for="__nav_3">
Configuration
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Configuration" data-md-level="1">
<label class="md-nav__title" for="__nav_3">
<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="../../setup.sh/" class="md-nav__link">
Your Best Friend setup.sh
</a>
</li>
<li class="md-nav__item">
<a href="../../environment/" class="md-nav__link">
Environment Variables
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_3_3" data-md-state="indeterminate" type="checkbox" id="__nav_3_3" checked>
<label class="md-nav__link" for="__nav_3_3">
User Management
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="User Management" data-md-level="2">
<label class="md-nav__title" for="__nav_3_3">
<span class="md-nav__icon md-icon"></span>
User Management
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../user-management/accounts/" class="md-nav__link">
Accounts
</a>
</li>
<li class="md-nav__item">
<a href="../../user-management/aliases/" class="md-nav__link">
Aliases
</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" data-md-toggle="__nav_3_4" type="checkbox" id="__nav_3_4" checked>
<label class="md-nav__link" for="__nav_3_4">
Best Practices
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Best Practices" data-md-level="2">
<label class="md-nav__title" for="__nav_3_4">
<span class="md-nav__icon md-icon"></span>
Best Practices
</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" data-md-toggle="toc" type="checkbox" id="__toc">
<label class="md-nav__link md-nav__link--active" for="__toc">
DKIM
<span class="md-nav__icon md-icon"></span>
</label>
<a href="./" class="md-nav__link md-nav__link--active">
DKIM
</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="#enabling-dkim-signature" class="md-nav__link">
Enabling DKIM Signature
</a>
</li>
<li class="md-nav__item">
<a href="#configuration-using-a-web-interface" class="md-nav__link">
Configuration using a Web Interface
</a>
</li>
<li class="md-nav__item">
<a href="#verify-only" class="md-nav__link">
Verify-Only
</a>
</li>
<li class="md-nav__item">
<a href="#switch-off-dkim" class="md-nav__link">
Switch Off DKIM
</a>
</li>
<li class="md-nav__item">
<a href="#debugging" class="md-nav__link">
Debugging
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="../dmarc/" class="md-nav__link">
DMARC
</a>
</li>
<li class="md-nav__item">
<a href="../spf/" class="md-nav__link">
SPF
</a>
</li>
<li class="md-nav__item">
<a href="../autodiscover/" class="md-nav__link">
Auto-discovery
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_3_5" data-md-state="indeterminate" type="checkbox" id="__nav_3_5" checked>
<label class="md-nav__link" for="__nav_3_5">
Security
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Security" data-md-level="2">
<label class="md-nav__title" for="__nav_3_5">
<span class="md-nav__icon md-icon"></span>
Security
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../security/understanding-the-ports/" class="md-nav__link">
Understanding the Ports
</a>
</li>
<li class="md-nav__item">
<a href="../../security/ssl/" class="md-nav__link">
SSL/TLS
</a>
</li>
<li class="md-nav__item">
<a href="../../security/fail2ban/" class="md-nav__link">
Fail2Ban
</a>
</li>
<li class="md-nav__item">
<a href="../../security/mail_crypt/" class="md-nav__link">
Mail Encryption
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_3_6" data-md-state="indeterminate" type="checkbox" id="__nav_3_6" checked>
<label class="md-nav__link" for="__nav_3_6">
Troubleshooting
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Troubleshooting" data-md-level="2">
<label class="md-nav__title" for="__nav_3_6">
<span class="md-nav__icon md-icon"></span>
Troubleshooting
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../troubleshooting/debugging/" class="md-nav__link">
Debugging
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="../../pop3/" class="md-nav__link">
Mail Delivery with POP3
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_3_8" data-md-state="indeterminate" type="checkbox" id="__nav_3_8" checked>
<label class="md-nav__link" for="__nav_3_8">
Advanced Configuration
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Advanced Configuration" data-md-level="2">
<label class="md-nav__title" for="__nav_3_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" data-md-toggle="__nav_3_8_2" data-md-state="indeterminate" type="checkbox" id="__nav_3_8_2" checked>
<label class="md-nav__link" for="__nav_3_8_2">
Maintenance
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Maintenance" data-md-level="3">
<label class="md-nav__title" for="__nav_3_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" data-md-toggle="__nav_3_8_3" data-md-state="indeterminate" type="checkbox" id="__nav_3_8_3" checked>
<label class="md-nav__link" for="__nav_3_8_3">
Override the Default Configs
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Override the Default Configs" data-md-level="3">
<label class="md-nav__title" for="__nav_3_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 md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_3_8_7" data-md-state="indeterminate" type="checkbox" id="__nav_3_8_7" checked>
<label class="md-nav__link" for="__nav_3_8_7">
Email Forwarding
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Email Forwarding" data-md-level="3">
<label class="md-nav__title" for="__nav_3_8_7">
<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>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_4" data-md-state="indeterminate" type="checkbox" id="__nav_4" checked>
<label class="md-nav__link" for="__nav_4">
Examples
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Examples" data-md-level="1">
<label class="md-nav__title" for="__nav_4">
<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" data-md-toggle="__nav_4_1" data-md-state="indeterminate" type="checkbox" id="__nav_4_1" checked>
<label class="md-nav__link" for="__nav_4_1">
Tutorials
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Tutorials" data-md-level="2">
<label class="md-nav__title" for="__nav_4_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>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle" data-md-toggle="__nav_4_2" data-md-state="indeterminate" type="checkbox" id="__nav_4_2" checked>
<label class="md-nav__link" for="__nav_4_2">
Use Cases
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Use Cases" data-md-level="2">
<label class="md-nav__title" for="__nav_4_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/uses-cases/forward-only-mailserver-with-ldap-authentication/" class="md-nav__link">
Forward-Only Mailserver with LDAP
</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" data-md-toggle="__nav_6" data-md-state="indeterminate" type="checkbox" id="__nav_6" checked>
<label class="md-nav__link" for="__nav_6">
Contributing
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" aria-label="Contributing" data-md-level="1">
<label class="md-nav__title" for="__nav_6">
<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/issues-and-pull-requests/" class="md-nav__link">
Issues and Pull Requests
</a>
</li>
<li class="md-nav__item">
<a href="../../../contributing/coding-style/" class="md-nav__link">
Coding Style
</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/documentation/" class="md-nav__link">
Documentation
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="https://hub.docker.com/repository/docker/mailserver/docker-mailserver" class="md-nav__link">
DockerHub
</a>
</li>
<li class="md-nav__item">
<a href="https://github.com/orgs/docker-mailserver/packages/container/package/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="#enabling-dkim-signature" class="md-nav__link">
Enabling DKIM Signature
</a>
</li>
<li class="md-nav__item">
<a href="#configuration-using-a-web-interface" class="md-nav__link">
Configuration using a Web Interface
</a>
</li>
<li class="md-nav__item">
<a href="#verify-only" class="md-nav__link">
Verify-Only
</a>
</li>
<li class="md-nav__item">
<a href="#switch-off-dkim" class="md-nav__link">
Switch Off DKIM
</a>
</li>
<li class="md-nav__item">
<a href="#debugging" class="md-nav__link">
Debugging
</a>
</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/best-practices/dkim.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="M20.71 7.04c.39-.39.39-1.04 0-1.41l-2.34-2.34c-.37-.39-1.02-.39-1.41 0l-1.84 1.83 3.75 3.75M3 17.25V21h3.75L17.81 9.93l-3.75-3.75L3 17.25z"/></svg>
</a>
<h1>DKIM</h1>
<p>DKIM is a security measure targeting email spoofing. It is greatly recommended one activates it.</p>
<div class="admonition seealso">
<p class="admonition-title">Seealso</p>
<p>See <a href="https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail">the Wikipedia page</a> for more details on DKIM.</p>
</div>
<h2 id="enabling-dkim-signature"><a class="toclink" href="#enabling-dkim-signature">Enabling DKIM Signature</a></h2>
<p>To enable DKIM signature, <strong>you must have created at least one email account</strong>. Once its done, just run the following command to generate the signature:</p>
<div class="highlight"><pre><span></span><code>./setup.sh config dkim
</code></pre></div>
<p>After generating DKIM keys, you should restart the mail server. DNS edits may take a few minutes to hours to propagate. The script assumes you're being in the directory where the <code>config/</code> directory is located. The default keysize when generating the signature is 4096 bits for now. If you need to change it (e.g. your DNS provider limits the size), then provide the size as the first parameter of the command:</p>
<div class="highlight"><pre><span></span><code>./setup.sh config dkim keysize &lt;keysize&gt;
</code></pre></div>
<p>For LDAP systems that do not have any directly created user account you can run the following command (since <code>8.0.0</code>) to generate the signature by additionally providing the desired domain name (if you have multiple domains use the command multiple times or provide a comma-separated list of domains): </p>
<div class="highlight"><pre><span></span><code>./setup.sh config dkim keysize &lt;key-size&gt; domain &lt;domain.tld&gt;<span class="o">[</span>,&lt;domain2.tld&gt;<span class="o">]</span>
</code></pre></div>
<p>Now the keys are generated, you can configure your DNS server with DKIM signature, simply by adding a TXT record. If you have direct access to your DNS zone file, then it's only a matter of pasting the content of <code>config/opendkim/keys/domain.tld/mail.txt</code> in your <code>domain.tld.hosts</code> zone.</p>
<div class="highlight"><pre><span></span><code><span class="gp">$ </span>dig mail._domainkey.domain.tld TXT
<span class="go">---</span>
<span class="go">;; ANSWER SECTION</span>
<span class="go">mail._domainkey.&lt;DOMAIN&gt; 300 IN TXT &quot;v=DKIM1; k=rsa; p=AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN/AZERTYUIOPQSDFGHJKLMWXCVBN&quot;</span>
</code></pre></div>
<h2 id="configuration-using-a-web-interface"><a class="toclink" href="#configuration-using-a-web-interface">Configuration using a Web Interface</a></h2>
<ol>
<li>Generate a new record of the type <code>TXT</code>.</li>
<li>Paste <code>mail._domainkey</code> the <code>Name</code> txt field.</li>
<li>In the <code>Target</code> or <code>Value</code> field fill in <code>v=DKIM1; k=rsa; p=AZERTYUGHJKLMWX...</code>.</li>
<li>In <code>TTL</code> (time to live): Time span in seconds. How long the DNS server should cache the <code>TXT</code> record.</li>
<li>Save.</li>
</ol>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Sometimes the key in <code>config/opendkim/keys/domain.tld/mail.txt</code> can be on multiple lines. If so then you need to concatenate the values in the TXT record:</p>
</div>
<div class="highlight"><pre><span></span><code><span class="gp">$ </span>dig mail._domainkey.domain.tld TXT
<span class="go">---</span>
<span class="go">;; ANSWER SECTION</span>
<span class="go">mail._domainkey.&lt;DOMAIN&gt; 300 IN TXT &quot;v=DKIM1; k=rsa; &quot;</span>
<span class="go"> &quot;p=AZERTYUIOPQSDF...&quot;</span>
<span class="go"> &quot;asdfQWERTYUIOPQSDF...&quot;</span>
</code></pre></div>
<p>The target (or value) field must then have all the parts together: <code>v=DKIM1; k=rsa; p=AZERTYUIOPQSDF...asdfQWERTYUIOPQSDF...</code></p>
<h2 id="verify-only"><a class="toclink" href="#verify-only">Verify-Only</a></h2>
<p>If you want DKIM to only <em>verify</em> incoming emails, the following version of <code>/etc/opendkim.conf</code> may be useful (right now there is no easy mechanism for installing it other than forking the repo):</p>
<div class="highlight"><pre><span></span><code><span class="c1"># This is a simple config file verifying messages only</span>
<span class="c1">#LogWhy yes</span>
<span class="na">Syslog yes</span>
<span class="na">SyslogSuccess yes</span>
<span class="na">Socket inet:12301@localhost</span>
<span class="na">PidFile /var/run/opendkim/opendkim.pid</span>
<span class="na">ReportAddress postmaster@my-domain.com</span>
<span class="na">SendReports yes</span>
<span class="na">Mode v</span>
</code></pre></div>
<h2 id="switch-off-dkim"><a class="toclink" href="#switch-off-dkim">Switch Off DKIM</a></h2>
<p>Simply remove the DKIM key by recreating (not just relaunching) the mailserver container.</p>
<h2 id="debugging"><a class="toclink" href="#debugging">Debugging</a></h2>
<ul>
<li><a href="https://addons.mozilla.org/en-US/thunderbird/addon/dkim-verifier">DKIM-verifer</a>: A add-on for the mail client Thunderbird.</li>
<li>You can debug your TXT records with the <code>dig</code> tool.</li>
</ul>
<div class="highlight"><pre><span></span><code><span class="gp">$ </span>dig TXT mail._domainkey.domain.tld
<span class="go">---</span>
<span class="go">; &lt;&lt;&gt;&gt; DiG 9.10.3-P4-Debian &lt;&lt;&gt;&gt; TXT mail._domainkey.domain.tld</span>
<span class="go">;; global options: +cmd</span>
<span class="go">;; Got answer:</span>
<span class="go">;; -&gt;&gt;HEADER&lt;&lt;- opcode: QUERY, status: NOERROR, id: 39669</span>
<span class="go">;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1</span>
<span class="go">;; OPT PSEUDOSECTION:</span>
<span class="go">; EDNS: version: 0, flags:; udp: 512</span>
<span class="go">;; QUESTION SECTION:</span>
<span class="go">;mail._domainkey.domain.tld. IN TXT</span>
<span class="go">;; ANSWER SECTION:</span>
<span class="go">mail._domainkey.domain.tld. 3600 IN TXT &quot;v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCxBSjG6RnWAdU3oOlqsdf2WC0FOUmU8uHVrzxPLW2R3yRBPGLrGO1++yy3tv6kMieWZwEBHVOdefM6uQOQsZ4brahu9lhG8sFLPX4MaKYN/NR6RK4gdjrZu+MYSdfk3THgSbNwIDAQAB&quot;</span>
<span class="go">;; Query time: 50 msec</span>
<span class="go">;; SERVER: 127.0.1.1#53(127.0.1.1)</span>
<span class="go">;; WHEN: Wed Sep 07 18:22:57 CEST 2016</span>
<span class="go">;; MSG SIZE rcvd: 310</span>
</code></pre></div>
<hr />
<div class="admonition warning">
<p class="admonition-title">Key sizes &gt;=4096-bit</p>
<p>Keys of 4096 bits could de denied by some mailservers. According to <a href="https://tools.ietf.org/html/rfc6376">https://tools.ietf.org/html/rfc6376</a> keys are preferably between 512 and 2048 bits. See issue <a href="https://github.com/docker-mailserver/docker-mailserver/issues/1854">#1854</a>.</p>
</div>
</article>
</div>
</div>
<a href="#" class="md-top md-icon" title="Back to top" data-md-component="top" data-md-state="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>
</a>
</main>
<footer class="md-footer">
<nav class="md-footer__inner md-grid" aria-label="Footer">
<a href="../../user-management/aliases/" class="md-footer__link md-footer__link--prev" rel="prev">
<div class="md-footer__button md-icon">
<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>
</div>
<div class="md-footer__title">
<div class="md-ellipsis">
<span class="md-footer__direction">
Previous
</span>
Aliases
</div>
</div>
</a>
<a href="../dmarc/" class="md-footer__link md-footer__link--next" rel="next">
<div class="md-footer__title">
<div class="md-ellipsis">
<span class="md-footer__direction">
Next
</span>
DMARC
</div>
</div>
<div class="md-footer__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M4 11v2h12l-5.5 5.5 1.42 1.42L19.84 12l-7.92-7.92L10.5 5.5 16 11H4z"/></svg>
</div>
</a>
</nav>
<div class="md-footer-meta md-typeset">
<div class="md-footer-meta__inner md-grid">
<div class="md-footer-copyright">
<div class="md-footer-copyright__highlight">
<p>&copy <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"], "translations": {"clipboard.copy": "Copy to clipboard", "clipboard.copied": "Copied to clipboard", "search.config.lang": "en", "search.config.pipeline": "trimmer, stopWordFilter", "search.config.separator": "[\\s\\-]+", "search.placeholder": "Search", "search.result.placeholder": "Type to start searching", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.term.missing": "Missing"}, "search": "../../../assets/javascripts/workers/search.4fa0e4ee.min.js", "version": {"provider": "mike"}}</script>
<script src="../../../assets/javascripts/bundle.1d3bfcf1.min.js"></script>
</body>
</html>
Reference in a new issue View git blame Copy permalink