| <!DOCTYPE html> |
| <html lang="en"> |
| <head> |
| <meta charset="utf-8"> |
| <meta name="viewport" content="width=device-width,initial-scale=1"> |
| <title>Post Office Protocol (POP) :: Apache James</title> |
| <meta name="generator" content="Antora 3.1.2"> |
| <link rel="stylesheet" href="../../../../_/css/site.css"> |
| </head> |
| <body class="article"> |
| <header class="header"> |
| <nav class="navbar"> |
| <div class="navbar-brand"> |
| <a class="navbar-item" href="https://james.apache.org"><img src="/_/img/james.svg" alt="james logo"> Apache James</a> |
| <button class="navbar-burger" data-target="topbar-nav"> |
| <span></span> |
| <span></span> |
| <span></span> |
| </button> |
| </div> |
| <div id="topbar-nav" class="navbar-menu"> |
| <div class="navbar-end"> |
| <a class="navbar-item" href="#">Home</a> |
| <div class="navbar-item has-dropdown is-hoverable"> |
| <a class="navbar-link" href="#">Products</a> |
| <div class="navbar-dropdown"> |
| <div class="navbar-item"><strong>James server</strong></div> |
| <a class="navbar-item" href="https://github.com/apache/james-project">Repository</a> |
| <a class="navbar-item" href="https://issues.apache.org/jira/projects/JAMES/issues">Issue Tracker</a> |
| <hr class="navbar-divider"> |
| <a class="navbar-item" href="https://james.apache.org/mime4j/index.html">Mime4J</a> |
| <a class="navbar-item" href="https://james.apache.org/jsieve/index.html">jSieve</a> |
| <a class="navbar-item" href="https://james.apache.org/jspf/index.html">jSPF</a> |
| <a class="navbar-item" href="https://james.apache.org/jdkim/index.html">jDKIM</a> |
| <a class="navbar-item" href="https://james.apache.org/hupa/index.html">HUPA</a> |
| </div> |
| </div> |
| <div class="navbar-item has-dropdown is-hoverable"> |
| <a class="navbar-link" href="#">Community</a> |
| <div class="navbar-dropdown"> |
| <!-- Not ideal but dropping the version in the href requires tweaking james-projet docs module first --> |
| <a class="navbar-item" href="/james-project/3.6.0/community/mailing-lists.html">Mailing lists</a> |
| <a class="navbar-item" href="https://gitter.im/apache/james-project"><svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 32 32" class="logo-gitter-sign" data-v-44ebcb1a=""><rect x="15" y="5" width="2" height="10"></rect> <rect x="10" y="5" width="2" height="20"></rect> <rect x="5" y="5" width="2" height="20"></rect> <rect width="2" height="15"></rect></svg> Gitter</a> |
| <a class="navbar-item" href="https://twitter.com/ApacheJames"> |
| <span class="icon"> |
| <svg aria-hidden="true" data-icon="twitter" role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"> |
| <path fill="#57aaee" d="M459.37 151.716c.325 4.548.325 9.097.325 13.645 0 138.72-105.583 298.558-298.558 298.558-59.452 0-114.68-17.219-161.137-47.106 8.447.974 16.568 1.299 25.34 1.299 49.055 0 94.213-16.568 130.274-44.832-46.132-.975-84.792-31.188-98.112-72.772 6.498.974 12.995 1.624 19.818 1.624 9.421 0 18.843-1.3 27.614-3.573-48.081-9.747-84.143-51.98-84.143-102.985v-1.299c13.969 7.797 30.214 12.67 47.431 13.319-28.264-18.843-46.781-51.005-46.781-87.391 0-19.492 5.197-37.36 14.294-52.954 51.655 63.675 129.3 105.258 216.365 109.807-1.624-7.797-2.599-15.918-2.599-24.04 0-57.828 46.782-104.934 104.934-104.934 30.213 0 57.502 12.67 76.67 33.137 23.715-4.548 46.456-13.32 66.599-25.34-7.798 24.366-24.366 44.833-46.132 57.827 21.117-2.273 41.584-8.122 60.426-16.243-14.292 20.791-32.161 39.308-52.628 54.253z"></path> |
| </svg> |
| </span> Twitter |
| </a> |
| <a class="navbar-item" href="#"> <svg class="octicon octicon-mark-github v-align-middle" viewBox="0 0 16 16" version="1.1" aria-hidden="true"><path fill-rule="evenodd" d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0016 8c0-4.42-3.58-8-8-8z"></path></svg> Github</a> |
| </div> |
| </div> |
| <!-- <div class="navbar-item"> |
| <span class="control"> |
| <a class="button is-primary" href="#">Download</a> |
| </span> |
| </div> --> |
| </div> |
| </div> |
| </nav> |
| </header> |
| <div class="body"> |
| <div class="nav-container" data-component="james-project" data-version="3.6.0"> |
| <aside class="nav"> |
| <div class="panels"> |
| <div class="nav-panel-menu is-active" data-panel="menu"> |
| <nav class="nav-menu"> |
| <button class="nav-menu-toggle" aria-label="Toggle expand/collapse all" style="display: none"></button> |
| <h3 class="title"><a href="../../index.html">Apache James Server</a></h3> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../index.html">Concepts</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../user/index.html">User Model</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../mail/index.html">Emails</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="#mail/messages/index.adoc">mail/messages/index.adoc</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="#mail/messages/imf.adoc">mail/messages/imf.adoc</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="#mail/messages/mime.adoc">mail/messages/mime.adoc</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="index.html">Protocols</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="smtp.html">SMTP</a> |
| </li> |
| <li class="nav-item is-current-page" data-depth="3"> |
| <a class="nav-link" href="pop.html">POP</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="imap.html">IMAP</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="jmap.html">JMAP</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="esmtp.html">ESMTP</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="lmtp.html">LMTP</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../storage/index.html">Storage</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../storage/mailbox.html">Mailboxes</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../storage/users.html">Users</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../processing/index.html">Processing</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../configuration.html">Configuration</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../glossary.html">Glossary</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/index.html">Servers</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/demo.html">Demo</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/5-minute-demo.html">Short Demo</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/15-minute-demo.html">Long Demo</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/basic/index.html">Basic</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/basic/context.html">Context</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/basic/objectives.html">Objectives</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/basic/concepts.html">Concepts</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/basic/architecture.html">Architecture</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/basic/conf/index.html">Configuration</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/basic/help.html">Help</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../servers/extendable.html">Extendable</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/distributed.html">Distributed</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/distributed/objectives.html">Objectives and motivation</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/distributed/architecture/index.html">Architecture</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/architecture/consistency-model.html">Consistency Model</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/architecture/specialized-instances.html">Specialized instances</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/distributed/run.html">Run</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="../../servers/distributed/run-docker.html">Run with docker</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/distributed/configure/index.html">Configuration</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <button class="nav-item-toggle"></button> |
| <span class="nav-text">Protocols</span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/imap.html">imapserver.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/jmap.html">jmap.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/jmx.html">jmx.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/smtp.html">smtpserver.xml & lmtpserver.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/smtp-hooks.html">Packaged SMTP hooks</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/pop3.html">pop3server.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/webadmin.html">webadmin.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/ssl.html">SSL & TLS</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <button class="nav-item-toggle"></button> |
| <span class="nav-text">Storage dependencies</span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/blobstore.html">blobstore.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/cassandra.html">cassandra.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/elasticsearch.html">elasticsearch.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/rabbitmq.html">rabbitmq.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/tika.html">tika.properties</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <button class="nav-item-toggle"></button> |
| <span class="nav-text">Core components</span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/batchsizes.html">batchsizes.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/dns.html">dnsservice.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/domainlist.html">domainlist.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/healthcheck.html">healthcheck.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/mailetcontainer.html">mailetcontainer.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/mailets.html">Packaged Mailets</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/matchers.html">Packaged Matchers</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/mailrepositorystore.html">mailrepositorystore.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/recipientrewritetable.html">recipientrewritetable.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/usersrepository.html">usersrepository.xml</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <button class="nav-item-toggle"></button> |
| <span class="nav-text">Extensions</span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/vault.html">deletedMessageVault.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/extensions.html">extensions.properties</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/listeners.html">listeners.xml</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/spam.html">Anti-Spam setup</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/remote-delivery-error-handling.html">About RemoteDelivery error handling</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/collecting-contacts.html">Contact collection</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/collecting-events.html">Event collection</a> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <a class="nav-link" href="../../servers/distributed/configure/dsn.html">ESMTP DSN support</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/distributed/operate/index.html">Operate</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/guide.html">Operator guide</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/logging.html">Logging</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/webadmin.html">WebAdmin REST administration API</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/metrics.html">Metrics</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/migrating.html">Migrating existing data</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/cli.html">Command Line Interface</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/operate/cassandra-migration.html">Cassandra migration</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../servers/distributed/extending/index.html">Extending server behavior</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/extending/mail-processing.html">Custom mail processing components</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/extending/mailbox-listeners.html">Custom Mailbox Listeners</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/extending/smtp-hooks.html">Custom SMTP hooks</a> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <a class="nav-link" href="../../servers/distributed/extending/webadmin-routes.html">Custom WebAdmin routes</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../servers/test.html">Test</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <a class="nav-link" href="../../customization/index.html">Customization</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <a class="nav-link" href="../../development/index.html">Developer Guide</a> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <button class="nav-item-toggle"></button> |
| <a class="nav-link" href="../../community/index.html">Community</a> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/mailing-lists.html">Mailing lists</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/contributing.html">Contributing</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/guidelines.html">Guidelines</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/download.html">Download releases</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/website.html">Building and publishing the website</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/release.html">Creating an official Apache James release</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <a class="nav-link" href="../../community/support.html">Professional support</a> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <button class="nav-item-toggle"></button> |
| <span class="nav-text">Apache Software Foundation</span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/">ASF</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/foundation/getinvolved.html">Get involved</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/foundation/faq.html">FAQ</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/licenses/">Licenses</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/security/">Security</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/foundation/sponsorship.html">Sponsorship</a> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <a class="nav-link" href="https://www.apache.org/foundation/thanks.html">Thanks</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </nav> |
| </div> |
| <div class="nav-panel-explore" data-panel="explore"> |
| <div class="context"> |
| <span class="title">Apache James Server</span> |
| <span class="version">3.6.0 Snapshot</span> |
| </div> |
| <ul class="components"> |
| <li class="component"> |
| <div class="title"><a href="../../../../james-distributed-app/3.8.1/index.html">Apache James Distributed Server</a></div> |
| <ul class="versions"> |
| <li class="version is-latest"> |
| <a href="../../../../james-distributed-app/3.8.1/index.html">3.8.1 SNAPSHOT</a> |
| </li> |
| </ul> |
| </li> |
| <li class="component is-current"> |
| <div class="title"><a href="../../../3.8.1/index.html">Apache James Server</a></div> |
| <ul class="versions"> |
| <li class="version is-latest"> |
| <a href="../../../3.8.1/index.html">3.8.1 SNAPSHOT</a> |
| </li> |
| <li class="version is-current"> |
| <a href="../../index.html">3.6.0 Snapshot</a> |
| </li> |
| </ul> |
| </li> |
| <li class="component"> |
| <div class="title"><a href="../../../../james-site/latest/index.html">Apache James Site</a></div> |
| <ul class="versions"> |
| <li class="version is-latest"> |
| <a href="../../../../james-site/latest/index.html">latest</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| </div> |
| </aside> |
| </div> |
| <main class="article"> |
| <div class="toolbar" role="navigation"> |
| <button class="nav-toggle"></button> |
| <a href="../../../../james-site/latest/homepage.html" class="home-link"></a> |
| <nav class="breadcrumbs" aria-label="breadcrumbs"> |
| <ul> |
| <li><a href="../../index.html">Apache James Server</a></li> |
| <li><a href="../index.html">Concepts</a></li> |
| <li><a href="index.html">Protocols</a></li> |
| <li><a href="pop.html">POP</a></li> |
| </ul> |
| </nav> |
| <div class="page-versions"> |
| <button class="version-menu-toggle" title="Show other versions of page">3.6.0 Snapshot</button> |
| <div class="version-menu"> |
| <a class="version" href="../../../3.8.1/concepts/protocols/pop.html">3.8.1 SNAPSHOT</a> |
| <a class="version is-current" href="pop.html">3.6.0 Snapshot</a> |
| </div> |
| </div> |
| <div class="edit-this-page"><a href="https://github.com/apache/james-project/blob/james-project-3.6.0/docs/modules/concepts/pages/protocols/pop.adoc">Edit this Page</a></div> |
| </div> |
| <div class="content"> |
| <aside class="toc sidebar" data-title="Contents" data-levels="2"> |
| <div class="toc-menu"></div> |
| </aside> |
| <article class="doc"> |
| <h1 class="page">Post Office Protocol (POP)</h1> |
| <div class="sect1"> |
| <h2 id="_overview"><a class="anchor" href="#_overview"></a>Overview</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>The <a href="https://en.wikipedia.org/wiki/Post_Office_Protocol">Post Office Protocol</a>, |
| or POP, is described in the original specification |
| as being "a simple method for workstations to dynamically access mail from |
| a <a href="../storage/index.html" class="xref page">mailbox server</a>" (though interestingly "mailbox server" |
| is never actually defined in this specification nor in later specifications. 🤔)</p> |
| </div> |
| <div class="paragraph"> |
| <p>POP was proposed as the first non-<a href="smtp.html" class="xref page">SMTP</a> protocol aimed |
| at users for the purpose of retrieving emails stored remotely for local consumption. |
| POP was developed in pre-spam days, so was inherently a non-secure protocol. |
| It has been updated several times to address several issues, including lack of |
| security, so that POP3 is now the current specification.</p> |
| </div> |
| <div class="paragraph"> |
| <p>As the name suggests, the protocol is modeled after a post office. The analogy being:</p> |
| </div> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p>The various SMTP servers along the transmission chain are like post offices</p> |
| </li> |
| <li> |
| <p>The user’s mail server is the local post office that will dispatch the mail to the recipient</p> |
| </li> |
| <li> |
| <p>The postman is, ummm, well no analogy is perfect 😬</p> |
| </li> |
| <li> |
| <p>The mail gets dropped into the user’s mailbox (though just to make the analogy even |
| muddier there is an option to leave a copy on the server)</p> |
| </li> |
| </ul> |
| </div> |
| <div class="paragraph"> |
| <p>Analogies aside, the protocol worked quite well for most users, and is still widely |
| in use today.</p> |
| </div> |
| <div class="paragraph"> |
| <p>POP requires essentially two pieces, the POP Client and the POP Server. How the |
| message gets initially delivered to the POP Server and how a message is managed |
| once delivered to the POP Client is out of scope of the POP protocol.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_specifications"><a class="anchor" href="#_specifications"></a>Specifications</h2> |
| <div class="sectionbody"> |
| <div class="sect2"> |
| <h3 id="_pop"><a class="anchor" href="#_pop"></a>POP</h3> |
| <div class="paragraph"> |
| <p>POP has been around since the early days of email. The original specification |
| <a href="#_rfc918">RFC918</a> was published in 1984.</p> |
| </div> |
| <div class="sect3"> |
| <h4 id="_rfc918"><a class="anchor" href="#_rfc918"></a>RFC918</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc918">RFC918</a> ("Post Office Protocol") was the original |
| specification published in 1984. The RFC "suggests a simple method for workstations |
| to dynamically access mail from a mailbox server." |
| Like <a href="smtp.html" class="xref page">SMTP</a> that came before it, POP is a session-based |
| protocol with a handful of defined commands. |
| This RFC was obsoleted shortly after its publication by <a href="#_rfc937">RFC937</a>.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect2"> |
| <h3 id="_pop2"><a class="anchor" href="#_pop2"></a>POP2</h3> |
| <div class="sect3"> |
| <h4 id="_rfc937"><a class="anchor" href="#_rfc937"></a>RFC937</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc937">RFC937</a> ("Post Office Protocol - Version 2") or more |
| commonly "POP2" was a revision of the original <a href="#_rfc918">RFC918</a> specification. POP2 specifies |
| connection over port 109, and clarifies that "it is important for the mailbox to be on |
| an 'always up' machine and that a workstation may be frequently powered down, or |
| otherwise unavailable as an SMTP server." In other words, as the Internet continued to |
| evolve, this specification was an attempt to evolve with it.</p> |
| </div> |
| <div class="paragraph"> |
| <p>POP2 was replaced by POP3, which was first published as <a href="#_rfc1081">RFC1081</a>.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect2"> |
| <h3 id="_pop3"><a class="anchor" href="#_pop3"></a>POP3</h3> |
| <div class="sect3"> |
| <h4 id="_rfc1081"><a class="anchor" href="#_rfc1081"></a>RFC1081</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc1081">RFC1081</a> ("Post Office Protocol - Version 3") |
| was the first published version of POP3, |
| made available in 1988. It adds additional functionality for managing mail, and |
| perhaps most importantly, it adds an authentication mechanism. This version was |
| obsoleted by <a href="#_rfc1225">RFC1225</a>.</p> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="_rfc1225"><a class="anchor" href="#_rfc1225"></a>RFC1225</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc1225">RFC1225</a> ("Post Office Protocol - Version 3") |
| obsoleted <a href="#_rfc1081">RFC1081</a>. It is described as being a "republication" of <a href="#_rfc1081">RFC1081</a>, |
| and does not appear to add anything significant. It was obsoleted by |
| <a href="#_rfc1460">RFC1460</a>.</p> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="_rfc1460"><a class="anchor" href="#_rfc1460"></a>RFC1460</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc1460">RFC1460</a> ("Post Office Protocol - Version 3") |
| provided some relatively minor updates to <a href="#_rfc1225">RFC1225</a>, and was itself obsoleted |
| about one year later by <a href="#_rfc1725">RFC1725</a>.</p> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="_rfc1725"><a class="anchor" href="#_rfc1725"></a>RFC1725</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc1725">RFC1725</a> ("Post Office Protocol - Version 3") |
| was again a relatively minor update of <a href="#_rfc1460">RFC1460</a>, and was itself obsoleted |
| about two years later by <a href="#_rfc1939">RFC1939</a>.</p> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="_rfc1939"><a class="anchor" href="#_rfc1939"></a>RFC1939</h4> |
| <div class="paragraph"> |
| <p><a href="https://tools.ietf.org/html/rfc1939">RFC1939</a> ("Post Office Protocol - Version 3") |
| is the most recent specification of POP3, and is the version in use today.</p> |
| </div> |
| <div class="paragraph"> |
| <p>This specification seems to imply that POP3 is used for "simple" transactions, |
| and for more "advanced" transactions <a href="imap.html" class="xref page">IMAP</a> is available.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect2"> |
| <h3 id="_pop4"><a class="anchor" href="#_pop4"></a>POP4</h3> |
| <div class="paragraph"> |
| <p>Although there was development on the <a href="http://www.pop4.org/">POP4</a> specification, |
| development appears to have stalled for several years, making POP3 the |
| still-current protocol.</p> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_related_concepts"><a class="anchor" href="#_related_concepts"></a>Related Concepts</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>POP relates to…​</p> |
| </div> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p><strong><a href="imap.html" class="xref page">IMAP</a></strong> as a "competing" protocol</p> |
| </li> |
| <li> |
| <p><strong><a href="../glossary.html#email_client" class="xref page">Email clients</a></strong>, in that the client acts as a POP Client</p> |
| </li> |
| <li> |
| <p><strong><a href="../storage/index.html" class="xref page">Storage</a></strong> in that messages are stored temporarily on |
| a ???? while awaiting transfer to the client</p> |
| </li> |
| <li> |
| <p><strong><a href="smtp.html" class="xref page">SMTP</a></strong>, in that messages will normally be |
| delivered to the IMAP Server via SMTP.</p> |
| </li> |
| </ul> |
| </div> |
| </div> |
| </div> |
| </article> |
| </div> |
| </main> |
| </div> |
| <footer class="footer"> |
| <p>This page was built using the Antora default UI.</p> |
| <p>The source code for this UI is licensed under the terms of the MPL-2.0 license.</p> |
| </footer> |
| <script id="site-script" src="../../../../_/js/site.js" data-ui-root-path="../../../../_"></script> |
| <script async src="../../../../_/js/vendor/highlight.js"></script> |
| </body> |
| </html> |