<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8" /> <title>smtpd — SMTP Server — Python 3.7.4 documentation</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/language_data.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 3.7.4 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="telnetlib — Telnet client" href="telnetlib.html" /> <link rel="prev" title="smtplib — SMTP protocol client" href="smtplib.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/smtpd.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> <script type="text/javascript" src="../_static/switchers.js"></script> <style> @media only screen { table.full-width-table { width: 100%; } } </style> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="telnetlib.html" title="telnetlib — Telnet client" accesskey="N">next</a> |</li> <li class="right" > <a href="smtplib.html" title="smtplib — SMTP protocol client" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">en</span> <span class="version_switcher_placeholder">3.7.4</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="internet.html" accesskey="U">Internet Protocols and Support</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-smtpd"> <span id="smtpd-smtp-server"></span><h1><a class="reference internal" href="#module-smtpd" title="smtpd: A SMTP server implementation in Python."><code class="xref py py-mod docutils literal notranslate"><span class="pre">smtpd</span></code></a> — SMTP Server<a class="headerlink" href="#module-smtpd" title="Permalink to this headline">¶</a></h1> <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.7/Lib/smtpd.py">Lib/smtpd.py</a></p> <hr class="docutils" /> <p>This module offers several classes to implement SMTP (email) servers.</p> <div class="admonition seealso"> <p class="admonition-title">See also</p> <p>The <a class="reference external" href="http://aiosmtpd.readthedocs.io/">aiosmtpd</a> package is a recommended replacement for this module. It is based on <a class="reference internal" href="asyncio.html#module-asyncio" title="asyncio: Asynchronous I/O."><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code></a> and provides a more straightforward API. <a class="reference internal" href="#module-smtpd" title="smtpd: A SMTP server implementation in Python."><code class="xref py py-mod docutils literal notranslate"><span class="pre">smtpd</span></code></a> should be considered deprecated.</p> </div> <p>Several server implementations are present; one is a generic do-nothing implementation, which can be overridden, while the other two offer specific mail-sending strategies.</p> <p>Additionally the SMTPChannel may be extended to implement very specific interaction behaviour with SMTP clients.</p> <p>The code supports <span class="target" id="index-0"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc5321.html"><strong>RFC 5321</strong></a>, plus the <span class="target" id="index-1"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc1870.html"><strong>RFC 1870</strong></a> SIZE and <span class="target" id="index-2"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc6531.html"><strong>RFC 6531</strong></a> SMTPUTF8 extensions.</p> <div class="section" id="smtpserver-objects"> <h2>SMTPServer Objects<a class="headerlink" href="#smtpserver-objects" title="Permalink to this headline">¶</a></h2> <dl class="class"> <dt id="smtpd.SMTPServer"> <em class="property">class </em><code class="descclassname">smtpd.</code><code class="descname">SMTPServer</code><span class="sig-paren">(</span><em>localaddr</em>, <em>remoteaddr</em>, <em>data_size_limit=33554432</em>, <em>map=None</em>, <em>enable_SMTPUTF8=False</em>, <em>decode_data=False</em><span class="sig-paren">)</span><a class="headerlink" href="#smtpd.SMTPServer" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new <a class="reference internal" href="#smtpd.SMTPServer" title="smtpd.SMTPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPServer</span></code></a> object, which binds to local address <em>localaddr</em>. It will treat <em>remoteaddr</em> as an upstream SMTP relayer. Both <em>localaddr</em> and <em>remoteaddr</em> should be a <a class="reference internal" href="socket.html#host-port"><span class="std std-ref">(host, port)</span></a> tuple. The object inherits from <a class="reference internal" href="asyncore.html#asyncore.dispatcher" title="asyncore.dispatcher"><code class="xref py py-class docutils literal notranslate"><span class="pre">asyncore.dispatcher</span></code></a>, and so will insert itself into <a class="reference internal" href="asyncore.html#module-asyncore" title="asyncore: A base class for developing asynchronous socket handling services."><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncore</span></code></a>’s event loop on instantiation.</p> <p><em>data_size_limit</em> specifies the maximum number of bytes that will be accepted in a <code class="docutils literal notranslate"><span class="pre">DATA</span></code> command. A value of <code class="docutils literal notranslate"><span class="pre">None</span></code> or <code class="docutils literal notranslate"><span class="pre">0</span></code> means no limit.</p> <p><em>map</em> is the socket map to use for connections (an initially empty dictionary is a suitable value). If not specified the <a class="reference internal" href="asyncore.html#module-asyncore" title="asyncore: A base class for developing asynchronous socket handling services."><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncore</span></code></a> global socket map is used.</p> <p><em>enable_SMTPUTF8</em> determines whether the <code class="docutils literal notranslate"><span class="pre">SMTPUTF8</span></code> extension (as defined in <span class="target" id="index-3"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc6531.html"><strong>RFC 6531</strong></a>) should be enabled. The default is <code class="docutils literal notranslate"><span class="pre">False</span></code>. When <code class="docutils literal notranslate"><span class="pre">True</span></code>, <code class="docutils literal notranslate"><span class="pre">SMTPUTF8</span></code> is accepted as a parameter to the <code class="docutils literal notranslate"><span class="pre">MAIL</span></code> command and when present is passed to <a class="reference internal" href="#smtpd.SMTPServer.process_message" title="smtpd.SMTPServer.process_message"><code class="xref py py-meth docutils literal notranslate"><span class="pre">process_message()</span></code></a> in the <code class="docutils literal notranslate"><span class="pre">kwargs['mail_options']</span></code> list. <em>decode_data</em> and <em>enable_SMTPUTF8</em> cannot be set to <code class="docutils literal notranslate"><span class="pre">True</span></code> at the same time.</p> <p><em>decode_data</em> specifies whether the data portion of the SMTP transaction should be decoded using UTF-8. When <em>decode_data</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code> (the default), the server advertises the <code class="docutils literal notranslate"><span class="pre">8BITMIME</span></code> extension (<span class="target" id="index-4"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc6152.html"><strong>RFC 6152</strong></a>), accepts the <code class="docutils literal notranslate"><span class="pre">BODY=8BITMIME</span></code> parameter to the <code class="docutils literal notranslate"><span class="pre">MAIL</span></code> command, and when present passes it to <a class="reference internal" href="#smtpd.SMTPServer.process_message" title="smtpd.SMTPServer.process_message"><code class="xref py py-meth docutils literal notranslate"><span class="pre">process_message()</span></code></a> in the <code class="docutils literal notranslate"><span class="pre">kwargs['mail_options']</span></code> list. <em>decode_data</em> and <em>enable_SMTPUTF8</em> cannot be set to <code class="docutils literal notranslate"><span class="pre">True</span></code> at the same time.</p> <dl class="method"> <dt id="smtpd.SMTPServer.process_message"> <code class="descname">process_message</code><span class="sig-paren">(</span><em>peer</em>, <em>mailfrom</em>, <em>rcpttos</em>, <em>data</em>, <em>**kwargs</em><span class="sig-paren">)</span><a class="headerlink" href="#smtpd.SMTPServer.process_message" title="Permalink to this definition">¶</a></dt> <dd><p>Raise a <a class="reference internal" href="exceptions.html#NotImplementedError" title="NotImplementedError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">NotImplementedError</span></code></a> exception. Override this in subclasses to do something useful with this message. Whatever was passed in the constructor as <em>remoteaddr</em> will be available as the <code class="xref py py-attr docutils literal notranslate"><span class="pre">_remoteaddr</span></code> attribute. <em>peer</em> is the remote host’s address, <em>mailfrom</em> is the envelope originator, <em>rcpttos</em> are the envelope recipients and <em>data</em> is a string containing the contents of the e-mail (which should be in <span class="target" id="index-5"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc5321.html"><strong>RFC 5321</strong></a> format).</p> <p>If the <em>decode_data</em> constructor keyword is set to <code class="docutils literal notranslate"><span class="pre">True</span></code>, the <em>data</em> argument will be a unicode string. If it is set to <code class="docutils literal notranslate"><span class="pre">False</span></code>, it will be a bytes object.</p> <p><em>kwargs</em> is a dictionary containing additional information. It is empty if <code class="docutils literal notranslate"><span class="pre">decode_data=True</span></code> was given as an init argument, otherwise it contains the following keys:</p> <blockquote> <div><dl class="simple"> <dt><em>mail_options</em>:</dt><dd><p>a list of all received parameters to the <code class="docutils literal notranslate"><span class="pre">MAIL</span></code> command (the elements are uppercase strings; example: <code class="docutils literal notranslate"><span class="pre">['BODY=8BITMIME',</span> <span class="pre">'SMTPUTF8']</span></code>).</p> </dd> <dt><em>rcpt_options</em>:</dt><dd><p>same as <em>mail_options</em> but for the <code class="docutils literal notranslate"><span class="pre">RCPT</span></code> command. Currently no <code class="docutils literal notranslate"><span class="pre">RCPT</span> <span class="pre">TO</span></code> options are supported, so for now this will always be an empty list.</p> </dd> </dl> </div></blockquote> <p>Implementations of <code class="docutils literal notranslate"><span class="pre">process_message</span></code> should use the <code class="docutils literal notranslate"><span class="pre">**kwargs</span></code> signature to accept arbitrary keyword arguments, since future feature enhancements may add keys to the kwargs dictionary.</p> <p>Return <code class="docutils literal notranslate"><span class="pre">None</span></code> to request a normal <code class="docutils literal notranslate"><span class="pre">250</span> <span class="pre">Ok</span></code> response; otherwise return the desired response string in <span class="target" id="index-6"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc5321.html"><strong>RFC 5321</strong></a> format.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPServer.channel_class"> <code class="descname">channel_class</code><a class="headerlink" href="#smtpd.SMTPServer.channel_class" title="Permalink to this definition">¶</a></dt> <dd><p>Override this in subclasses to use a custom <a class="reference internal" href="#smtpd.SMTPChannel" title="smtpd.SMTPChannel"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPChannel</span></code></a> for managing SMTP clients.</p> </dd></dl> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.4: </span>The <em>map</em> constructor argument.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.5: </span><em>localaddr</em> and <em>remoteaddr</em> may now contain IPv6 addresses.</p> </div> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.5: </span>The <em>decode_data</em> and <em>enable_SMTPUTF8</em> constructor parameters, and the <em>kwargs</em> parameter to <a class="reference internal" href="#smtpd.SMTPServer.process_message" title="smtpd.SMTPServer.process_message"><code class="xref py py-meth docutils literal notranslate"><span class="pre">process_message()</span></code></a> when <em>decode_data</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span><em>decode_data</em> is now <code class="docutils literal notranslate"><span class="pre">False</span></code> by default.</p> </div> </dd></dl> </div> <div class="section" id="debuggingserver-objects"> <h2>DebuggingServer Objects<a class="headerlink" href="#debuggingserver-objects" title="Permalink to this headline">¶</a></h2> <dl class="class"> <dt id="smtpd.DebuggingServer"> <em class="property">class </em><code class="descclassname">smtpd.</code><code class="descname">DebuggingServer</code><span class="sig-paren">(</span><em>localaddr</em>, <em>remoteaddr</em><span class="sig-paren">)</span><a class="headerlink" href="#smtpd.DebuggingServer" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new debugging server. Arguments are as per <a class="reference internal" href="#smtpd.SMTPServer" title="smtpd.SMTPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPServer</span></code></a>. Messages will be discarded, and printed on stdout.</p> </dd></dl> </div> <div class="section" id="pureproxy-objects"> <h2>PureProxy Objects<a class="headerlink" href="#pureproxy-objects" title="Permalink to this headline">¶</a></h2> <dl class="class"> <dt id="smtpd.PureProxy"> <em class="property">class </em><code class="descclassname">smtpd.</code><code class="descname">PureProxy</code><span class="sig-paren">(</span><em>localaddr</em>, <em>remoteaddr</em><span class="sig-paren">)</span><a class="headerlink" href="#smtpd.PureProxy" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new pure proxy server. Arguments are as per <a class="reference internal" href="#smtpd.SMTPServer" title="smtpd.SMTPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPServer</span></code></a>. Everything will be relayed to <em>remoteaddr</em>. Note that running this has a good chance to make you into an open relay, so please be careful.</p> </dd></dl> </div> <div class="section" id="mailmanproxy-objects"> <h2>MailmanProxy Objects<a class="headerlink" href="#mailmanproxy-objects" title="Permalink to this headline">¶</a></h2> <dl class="class"> <dt id="smtpd.MailmanProxy"> <em class="property">class </em><code class="descclassname">smtpd.</code><code class="descname">MailmanProxy</code><span class="sig-paren">(</span><em>localaddr</em>, <em>remoteaddr</em><span class="sig-paren">)</span><a class="headerlink" href="#smtpd.MailmanProxy" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new pure proxy server. Arguments are as per <a class="reference internal" href="#smtpd.SMTPServer" title="smtpd.SMTPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPServer</span></code></a>. Everything will be relayed to <em>remoteaddr</em>, unless local mailman configurations knows about an address, in which case it will be handled via mailman. Note that running this has a good chance to make you into an open relay, so please be careful.</p> </dd></dl> </div> <div class="section" id="smtpchannel-objects"> <h2>SMTPChannel Objects<a class="headerlink" href="#smtpchannel-objects" title="Permalink to this headline">¶</a></h2> <dl class="class"> <dt id="smtpd.SMTPChannel"> <em class="property">class </em><code class="descclassname">smtpd.</code><code class="descname">SMTPChannel</code><span class="sig-paren">(</span><em>server</em>, <em>conn</em>, <em>addr</em>, <em>data_size_limit=33554432</em>, <em>map=None</em>, <em>enable_SMTPUTF8=False</em>, <em>decode_data=False</em><span class="sig-paren">)</span><a class="headerlink" href="#smtpd.SMTPChannel" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new <a class="reference internal" href="#smtpd.SMTPChannel" title="smtpd.SMTPChannel"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPChannel</span></code></a> object which manages the communication between the server and a single SMTP client.</p> <p><em>conn</em> and <em>addr</em> are as per the instance variables described below.</p> <p><em>data_size_limit</em> specifies the maximum number of bytes that will be accepted in a <code class="docutils literal notranslate"><span class="pre">DATA</span></code> command. A value of <code class="docutils literal notranslate"><span class="pre">None</span></code> or <code class="docutils literal notranslate"><span class="pre">0</span></code> means no limit.</p> <p><em>enable_SMTPUTF8</em> determines whether the <code class="docutils literal notranslate"><span class="pre">SMTPUTF8</span></code> extension (as defined in <span class="target" id="index-7"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc6531.html"><strong>RFC 6531</strong></a>) should be enabled. The default is <code class="docutils literal notranslate"><span class="pre">False</span></code>. <em>decode_data</em> and <em>enable_SMTPUTF8</em> cannot be set to <code class="docutils literal notranslate"><span class="pre">True</span></code> at the same time.</p> <p>A dictionary can be specified in <em>map</em> to avoid using a global socket map.</p> <p><em>decode_data</em> specifies whether the data portion of the SMTP transaction should be decoded using UTF-8. The default is <code class="docutils literal notranslate"><span class="pre">False</span></code>. <em>decode_data</em> and <em>enable_SMTPUTF8</em> cannot be set to <code class="docutils literal notranslate"><span class="pre">True</span></code> at the same time.</p> <p>To use a custom SMTPChannel implementation you need to override the <a class="reference internal" href="#smtpd.SMTPServer.channel_class" title="smtpd.SMTPServer.channel_class"><code class="xref py py-attr docutils literal notranslate"><span class="pre">SMTPServer.channel_class</span></code></a> of your <a class="reference internal" href="#smtpd.SMTPServer" title="smtpd.SMTPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPServer</span></code></a>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.5: </span>The <em>decode_data</em> and <em>enable_SMTPUTF8</em> parameters were added.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span><em>decode_data</em> is now <code class="docutils literal notranslate"><span class="pre">False</span></code> by default.</p> </div> <p>The <a class="reference internal" href="#smtpd.SMTPChannel" title="smtpd.SMTPChannel"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPChannel</span></code></a> has the following instance variables:</p> <dl class="attribute"> <dt id="smtpd.SMTPChannel.smtp_server"> <code class="descname">smtp_server</code><a class="headerlink" href="#smtpd.SMTPChannel.smtp_server" title="Permalink to this definition">¶</a></dt> <dd><p>Holds the <a class="reference internal" href="#smtpd.SMTPServer" title="smtpd.SMTPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPServer</span></code></a> that spawned this channel.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.conn"> <code class="descname">conn</code><a class="headerlink" href="#smtpd.SMTPChannel.conn" title="Permalink to this definition">¶</a></dt> <dd><p>Holds the socket object connecting to the client.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.addr"> <code class="descname">addr</code><a class="headerlink" href="#smtpd.SMTPChannel.addr" title="Permalink to this definition">¶</a></dt> <dd><p>Holds the address of the client, the second value returned by <a class="reference internal" href="socket.html#socket.socket.accept" title="socket.socket.accept"><code class="xref py py-func docutils literal notranslate"><span class="pre">socket.accept</span></code></a></p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.received_lines"> <code class="descname">received_lines</code><a class="headerlink" href="#smtpd.SMTPChannel.received_lines" title="Permalink to this definition">¶</a></dt> <dd><p>Holds a list of the line strings (decoded using UTF-8) received from the client. The lines have their <code class="docutils literal notranslate"><span class="pre">"\r\n"</span></code> line ending translated to <code class="docutils literal notranslate"><span class="pre">"\n"</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.smtp_state"> <code class="descname">smtp_state</code><a class="headerlink" href="#smtpd.SMTPChannel.smtp_state" title="Permalink to this definition">¶</a></dt> <dd><p>Holds the current state of the channel. This will be either <code class="xref py py-attr docutils literal notranslate"><span class="pre">COMMAND</span></code> initially and then <code class="xref py py-attr docutils literal notranslate"><span class="pre">DATA</span></code> after the client sends a “DATA” line.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.seen_greeting"> <code class="descname">seen_greeting</code><a class="headerlink" href="#smtpd.SMTPChannel.seen_greeting" title="Permalink to this definition">¶</a></dt> <dd><p>Holds a string containing the greeting sent by the client in its “HELO”.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.mailfrom"> <code class="descname">mailfrom</code><a class="headerlink" href="#smtpd.SMTPChannel.mailfrom" title="Permalink to this definition">¶</a></dt> <dd><p>Holds a string containing the address identified in the “MAIL FROM:” line from the client.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.rcpttos"> <code class="descname">rcpttos</code><a class="headerlink" href="#smtpd.SMTPChannel.rcpttos" title="Permalink to this definition">¶</a></dt> <dd><p>Holds a list of strings containing the addresses identified in the “RCPT TO:” lines from the client.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.received_data"> <code class="descname">received_data</code><a class="headerlink" href="#smtpd.SMTPChannel.received_data" title="Permalink to this definition">¶</a></dt> <dd><p>Holds a string containing all of the data sent by the client during the DATA state, up to but not including the terminating <code class="docutils literal notranslate"><span class="pre">"\r\n.\r\n"</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.fqdn"> <code class="descname">fqdn</code><a class="headerlink" href="#smtpd.SMTPChannel.fqdn" title="Permalink to this definition">¶</a></dt> <dd><p>Holds the fully-qualified domain name of the server as returned by <a class="reference internal" href="socket.html#socket.getfqdn" title="socket.getfqdn"><code class="xref py py-func docutils literal notranslate"><span class="pre">socket.getfqdn()</span></code></a>.</p> </dd></dl> <dl class="attribute"> <dt id="smtpd.SMTPChannel.peer"> <code class="descname">peer</code><a class="headerlink" href="#smtpd.SMTPChannel.peer" title="Permalink to this definition">¶</a></dt> <dd><p>Holds the name of the client peer as returned by <code class="docutils literal notranslate"><span class="pre">conn.getpeername()</span></code> where <code class="docutils literal notranslate"><span class="pre">conn</span></code> is <a class="reference internal" href="#smtpd.SMTPChannel.conn" title="smtpd.SMTPChannel.conn"><code class="xref py py-attr docutils literal notranslate"><span class="pre">conn</span></code></a>.</p> </dd></dl> <p>The <a class="reference internal" href="#smtpd.SMTPChannel" title="smtpd.SMTPChannel"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPChannel</span></code></a> operates by invoking methods named <code class="docutils literal notranslate"><span class="pre">smtp_<command></span></code> upon reception of a command line from the client. Built into the base <a class="reference internal" href="#smtpd.SMTPChannel" title="smtpd.SMTPChannel"><code class="xref py py-class docutils literal notranslate"><span class="pre">SMTPChannel</span></code></a> class are methods for handling the following commands (and responding to them appropriately):</p> <table class="docutils align-center"> <colgroup> <col style="width: 11%" /> <col style="width: 89%" /> </colgroup> <thead> <tr class="row-odd"><th class="head"><p>Command</p></th> <th class="head"><p>Action taken</p></th> </tr> </thead> <tbody> <tr class="row-even"><td><p>HELO</p></td> <td><p>Accepts the greeting from the client and stores it in <a class="reference internal" href="#smtpd.SMTPChannel.seen_greeting" title="smtpd.SMTPChannel.seen_greeting"><code class="xref py py-attr docutils literal notranslate"><span class="pre">seen_greeting</span></code></a>. Sets server to base command mode.</p></td> </tr> <tr class="row-odd"><td><p>EHLO</p></td> <td><p>Accepts the greeting from the client and stores it in <a class="reference internal" href="#smtpd.SMTPChannel.seen_greeting" title="smtpd.SMTPChannel.seen_greeting"><code class="xref py py-attr docutils literal notranslate"><span class="pre">seen_greeting</span></code></a>. Sets server to extended command mode.</p></td> </tr> <tr class="row-even"><td><p>NOOP</p></td> <td><p>Takes no action.</p></td> </tr> <tr class="row-odd"><td><p>QUIT</p></td> <td><p>Closes the connection cleanly.</p></td> </tr> <tr class="row-even"><td><p>MAIL</p></td> <td><p>Accepts the “MAIL FROM:” syntax and stores the supplied address as <a class="reference internal" href="#smtpd.SMTPChannel.mailfrom" title="smtpd.SMTPChannel.mailfrom"><code class="xref py py-attr docutils literal notranslate"><span class="pre">mailfrom</span></code></a>. In extended command mode, accepts the <span class="target" id="index-8"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc1870.html"><strong>RFC 1870</strong></a> SIZE attribute and responds appropriately based on the value of <em>data_size_limit</em>.</p></td> </tr> <tr class="row-odd"><td><p>RCPT</p></td> <td><p>Accepts the “RCPT TO:” syntax and stores the supplied addresses in the <a class="reference internal" href="#smtpd.SMTPChannel.rcpttos" title="smtpd.SMTPChannel.rcpttos"><code class="xref py py-attr docutils literal notranslate"><span class="pre">rcpttos</span></code></a> list.</p></td> </tr> <tr class="row-even"><td><p>RSET</p></td> <td><p>Resets the <a class="reference internal" href="#smtpd.SMTPChannel.mailfrom" title="smtpd.SMTPChannel.mailfrom"><code class="xref py py-attr docutils literal notranslate"><span class="pre">mailfrom</span></code></a>, <a class="reference internal" href="#smtpd.SMTPChannel.rcpttos" title="smtpd.SMTPChannel.rcpttos"><code class="xref py py-attr docutils literal notranslate"><span class="pre">rcpttos</span></code></a>, and <a class="reference internal" href="#smtpd.SMTPChannel.received_data" title="smtpd.SMTPChannel.received_data"><code class="xref py py-attr docutils literal notranslate"><span class="pre">received_data</span></code></a>, but not the greeting.</p></td> </tr> <tr class="row-odd"><td><p>DATA</p></td> <td><p>Sets the internal state to <code class="xref py py-attr docutils literal notranslate"><span class="pre">DATA</span></code> and stores remaining lines from the client in <a class="reference internal" href="#smtpd.SMTPChannel.received_data" title="smtpd.SMTPChannel.received_data"><code class="xref py py-attr docutils literal notranslate"><span class="pre">received_data</span></code></a> until the terminator <code class="docutils literal notranslate"><span class="pre">"\r\n.\r\n"</span></code> is received.</p></td> </tr> <tr class="row-even"><td><p>HELP</p></td> <td><p>Returns minimal information on command syntax</p></td> </tr> <tr class="row-odd"><td><p>VRFY</p></td> <td><p>Returns code 252 (the server doesn’t know if the address is valid)</p></td> </tr> <tr class="row-even"><td><p>EXPN</p></td> <td><p>Reports that the command is not implemented.</p></td> </tr> </tbody> </table> </dd></dl> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table of Contents</a></h3> <ul> <li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">smtpd</span></code> — SMTP Server</a><ul> <li><a class="reference internal" href="#smtpserver-objects">SMTPServer Objects</a></li> <li><a class="reference internal" href="#debuggingserver-objects">DebuggingServer Objects</a></li> <li><a class="reference internal" href="#pureproxy-objects">PureProxy Objects</a></li> <li><a class="reference internal" href="#mailmanproxy-objects">MailmanProxy Objects</a></li> <li><a class="reference internal" href="#smtpchannel-objects">SMTPChannel Objects</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="smtplib.html" title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">smtplib</span></code> — SMTP protocol client</a></p> <h4>Next topic</h4> <p class="topless"><a href="telnetlib.html" title="next chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">telnetlib</span></code> — Telnet client</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.7/Doc/library/smtpd.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="telnetlib.html" title="telnetlib — Telnet client" >next</a> |</li> <li class="right" > <a href="smtplib.html" title="smtplib — SMTP protocol client" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; 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