472 lines
31 KiB
HTML
472 lines
31 KiB
HTML
<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
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"https://www.w3.org/TR/html4/loose.dtd">
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<html> <head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link rel='stylesheet' type='text/css' href='postfix-doc.css'>
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<title> Postfix manual - postscreen(8) </title>
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</head> <body> <pre>
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POSTSCREEN(8) POSTSCREEN(8)
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<b><a name="name">NAME</a></b>
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postscreen - Postfix zombie blocker
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<b><a name="synopsis">SYNOPSIS</a></b>
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<b>postscreen</b> [generic Postfix daemon options]
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<b><a name="description">DESCRIPTION</a></b>
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The Postfix <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server provides additional protection against
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mail server overload. One <a href="postscreen.8.html"><b>postscreen</b>(8)</a> process handles multiple
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inbound SMTP connections, and decides which clients may talk to a Post-
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fix SMTP server process. By keeping spambots away, <a href="postscreen.8.html"><b>postscreen</b>(8)</a>
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leaves more SMTP server processes available for legitimate clients, and
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delays the onset of server overload conditions.
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This program should not be used on SMTP ports that receive mail from
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end-user clients (MUAs). In a typical deployment, <a href="postscreen.8.html"><b>postscreen</b>(8)</a> handles
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the MX service on TCP port 25, and <a href="smtpd.8.html"><b>smtpd</b>(8)</a> receives mail from MUAs on
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the <b>submission</b> service (TCP port 587) which requires client authentica-
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tion. Alternatively, a site could set up a dedicated, non-postscreen,
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"port 25" server that provides <b>submission</b> service and client authenti-
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cation, but no MX service.
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<a href="postscreen.8.html"><b>postscreen</b>(8)</a> maintains a temporary allowlist for clients that have
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passed a number of tests. When an SMTP client IP address is
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allowlisted, <a href="postscreen.8.html"><b>postscreen</b>(8)</a> hands off the connection immediately to a
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Postfix SMTP server process. This minimizes the overhead for legitimate
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mail.
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By default, <a href="postscreen.8.html"><b>postscreen</b>(8)</a> logs statistics and hands off each connection
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to a Postfix SMTP server process, while excluding clients in <a href="postconf.5.html#mynetworks">mynetworks</a>
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from all tests (primarily, to avoid problems with non-standard SMTP
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implementations in network appliances). This default mode blocks no
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clients, and is useful for non-destructive testing.
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In a typical production setting, <a href="postscreen.8.html"><b>postscreen</b>(8)</a> is configured to reject
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mail from clients that fail one or more tests. <a href="postscreen.8.html"><b>postscreen</b>(8)</a> logs
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rejected mail with the client address, helo, sender and recipient
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information.
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<a href="postscreen.8.html"><b>postscreen</b>(8)</a> is not an SMTP proxy; this is intentional. The purpose
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is to keep spambots away from Postfix SMTP server processes, while min-
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imizing overhead for legitimate traffic.
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<b><a name="security">SECURITY</a></b>
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The <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server is moderately security-sensitive. It talks to
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untrusted clients on the network. The process can be run chrooted at
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fixed low privilege.
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<b><a name="standards">STANDARDS</a></b>
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<a href="https://tools.ietf.org/html/rfc821">RFC 821</a> (SMTP protocol)
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<a href="https://tools.ietf.org/html/rfc1123">RFC 1123</a> (Host requirements)
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<a href="https://tools.ietf.org/html/rfc1652">RFC 1652</a> (8bit-MIME transport)
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<a href="https://tools.ietf.org/html/rfc1869">RFC 1869</a> (SMTP service extensions)
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<a href="https://tools.ietf.org/html/rfc1870">RFC 1870</a> (Message Size Declaration)
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<a href="https://tools.ietf.org/html/rfc1985">RFC 1985</a> (ETRN command)
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<a href="https://tools.ietf.org/html/rfc2034">RFC 2034</a> (SMTP Enhanced Status Codes)
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<a href="https://tools.ietf.org/html/rfc2821">RFC 2821</a> (SMTP protocol)
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Not: <a href="https://tools.ietf.org/html/rfc2920">RFC 2920</a> (SMTP Pipelining)
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<a href="https://tools.ietf.org/html/rfc3030">RFC 3030</a> (CHUNKING without BINARYMIME)
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<a href="https://tools.ietf.org/html/rfc3207">RFC 3207</a> (STARTTLS command)
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<a href="https://tools.ietf.org/html/rfc3461">RFC 3461</a> (SMTP DSN Extension)
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<a href="https://tools.ietf.org/html/rfc3463">RFC 3463</a> (Enhanced Status Codes)
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<a href="https://tools.ietf.org/html/rfc5321">RFC 5321</a> (SMTP protocol, including multi-line 220 banners)
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<b><a name="diagnostics">DIAGNOSTICS</a></b>
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Problems and transactions are logged to <b>syslogd</b>(8) or <a href="postlogd.8.html"><b>postlogd</b>(8)</a>.
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<b><a name="bugs">BUGS</a></b>
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The <a href="postscreen.8.html"><b>postscreen</b>(8)</a> built-in SMTP protocol engine currently does not
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announce support for AUTH, XCLIENT or XFORWARD. If you need to make
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these services available on port 25, then do not enable the optional
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"after 220 server greeting" tests.
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The optional "after 220 server greeting" tests may result in unexpected
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delivery delays from senders that retry email delivery from a different
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IP address. Reason: after passing these tests a new client must dis-
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connect, and reconnect from the same IP address before it can deliver
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mail. See <a href="POSTSCREEN_README.html">POSTSCREEN_README</a>, section "Tests after the 220 SMTP server
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greeting", for a discussion.
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<b><a name="configuration_parameters">CONFIGURATION PARAMETERS</a></b>
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Changes to <a href="postconf.5.html">main.cf</a> are not picked up automatically, as <a href="postscreen.8.html"><b>postscreen</b>(8)</a>
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processes may run for several hours. Use the command "postfix reload"
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after a configuration change.
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The text below provides only a parameter summary. See <a href="postconf.5.html"><b>postconf</b>(5)</a> for
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more details including examples.
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NOTE: Some <a href="postscreen.8.html"><b>postscreen</b>(8)</a> parameters implement stress-dependent behav-
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ior. This is supported only when the default parameter value is
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stress-dependent (that is, it looks like ${stress?{X}:{Y}}, or it is
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the $<i>name</i> of an smtpd parameter with a stress-dependent default).
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Other parameters always evaluate as if the <b>stress</b> parameter value is
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the empty string.
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<b><a name="compatibility_controls">COMPATIBILITY CONTROLS</a></b>
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<b><a href="postconf.5.html#postscreen_command_filter">postscreen_command_filter</a> ($<a href="postconf.5.html#smtpd_command_filter">smtpd_command_filter</a>)</b>
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A mechanism to transform commands from remote SMTP clients.
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<b><a href="postconf.5.html#postscreen_discard_ehlo_keyword_address_maps">postscreen_discard_ehlo_keyword_address_maps</a> ($<a href="postconf.5.html#smtpd_discard_ehlo_keyword_address_maps">smtpd_discard_ehlo_key</a>-</b>
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<b><a href="postconf.5.html#smtpd_discard_ehlo_keyword_address_maps">word_address_maps</a>)</b>
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Lookup tables, indexed by the remote SMTP client address, with
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case insensitive lists of EHLO keywords (pipelining, starttls,
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auth, etc.) that the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server will not send in the
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EHLO response to a remote SMTP client.
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<b><a href="postconf.5.html#postscreen_discard_ehlo_keywords">postscreen_discard_ehlo_keywords</a> ($<a href="postconf.5.html#smtpd_discard_ehlo_keywords">smtpd_discard_ehlo_keywords</a>)</b>
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A case insensitive list of EHLO keywords (pipelining, starttls,
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auth, etc.) that the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server will not send in the
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EHLO response to a remote SMTP client.
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Available in Postfix version 3.1 and later:
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<b><a href="postconf.5.html#dns_ncache_ttl_fix_enable">dns_ncache_ttl_fix_enable</a> (no)</b>
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Enable a workaround for future libc incompatibility.
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Available in Postfix version 3.4 and later:
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<b><a href="postconf.5.html#postscreen_reject_footer_maps">postscreen_reject_footer_maps</a> ($<a href="postconf.5.html#smtpd_reject_footer_maps">smtpd_reject_footer_maps</a>)</b>
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Optional lookup table for information that is appended after a
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4XX or 5XX <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server response.
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Available in Postfix 3.6 and later:
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<b><a href="postconf.5.html#respectful_logging">respectful_logging</a> (see 'postconf -d' output)</b>
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Avoid logging that implies white is better than black.
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<b><a name="trouble_shooting_controls">TROUBLE SHOOTING CONTROLS</a></b>
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<b><a href="postconf.5.html#postscreen_expansion_filter">postscreen_expansion_filter</a> (see 'postconf -d' output)</b>
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List of characters that are permitted in
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<a href="postconf.5.html#postscreen_reject_footer">postscreen_reject_footer</a> attribute expansions.
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<b><a href="postconf.5.html#postscreen_reject_footer">postscreen_reject_footer</a> ($<a href="postconf.5.html#smtpd_reject_footer">smtpd_reject_footer</a>)</b>
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Optional information that is appended after a 4XX or 5XX
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<a href="postscreen.8.html"><b>postscreen</b>(8)</a> server response.
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<b><a href="postconf.5.html#soft_bounce">soft_bounce</a> (no)</b>
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Safety net to keep mail queued that would otherwise be returned
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to the sender.
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<b><a name="before-postscreen_proxy_agent">BEFORE-POSTSCREEN PROXY AGENT</a></b>
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Available in Postfix version 2.10 and later:
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<b><a href="postconf.5.html#postscreen_upstream_proxy_protocol">postscreen_upstream_proxy_protocol</a> (empty)</b>
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The name of the proxy protocol used by an optional
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before-postscreen proxy agent.
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<b><a href="postconf.5.html#postscreen_upstream_proxy_timeout">postscreen_upstream_proxy_timeout</a> (5s)</b>
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The time limit for the proxy protocol specified with the
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<a href="postconf.5.html#postscreen_upstream_proxy_protocol">postscreen_upstream_proxy_protocol</a> parameter.
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<b>PERMANENT ALLOW/DENYLIST TEST</b>
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This test is executed immediately after a remote SMTP client connects.
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If a client is permanently allowlisted, the client will be handed off
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immediately to a Postfix SMTP server process.
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<b><a href="postconf.5.html#postscreen_access_list">postscreen_access_list</a> (<a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>)</b>
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Permanent allow/denylist for remote SMTP client IP addresses.
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<b><a href="postconf.5.html#postscreen_blacklist_action">postscreen_blacklist_action</a> (ignore)</b>
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Renamed to <a href="postconf.5.html#postscreen_denylist_action">postscreen_denylist_action</a> in Postfix 3.6.
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<b><a name="mail_exchanger_policy_tests">MAIL EXCHANGER POLICY TESTS</a></b>
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When <a href="postscreen.8.html"><b>postscreen</b>(8)</a> is configured to monitor all primary and backup MX
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addresses, it can refuse to allowlist clients that connect to a backup
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MX address only. For small sites, this requires configuring primary and
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backup MX addresses on the same MTA. Larger sites would have to share
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the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> cache between primary and backup MTAs, which would
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introduce a common point of failure.
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<b><a href="postconf.5.html#postscreen_allowlist_interfaces">postscreen_allowlist_interfaces</a> (<a href="DATABASE_README.html#types">static</a>:all)</b>
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A list of local <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server IP addresses where a
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non-allowlisted remote SMTP client can obtain <a href="postscreen.8.html"><b>postscreen</b>(8)</a>'s
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temporary allowlist status.
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<b><a name="before_220_greeting_tests">BEFORE 220 GREETING TESTS</a></b>
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These tests are executed before the remote SMTP client receives the
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"220 servername" greeting. If no tests remain after the successful com-
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pletion of this phase, the client will be handed off immediately to a
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Postfix SMTP server process.
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<b><a href="postconf.5.html#dnsblog_service_name">dnsblog_service_name</a> (dnsblog)</b>
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The name of the <a href="dnsblog.8.html"><b>dnsblog</b>(8)</a> service entry in <a href="master.5.html">master.cf</a>.
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<b><a href="postconf.5.html#postscreen_dnsbl_action">postscreen_dnsbl_action</a> (ignore)</b>
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The action that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> takes when a remote SMTP client's
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combined DNSBL score is equal to or greater than a threshold (as
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defined with the <a href="postconf.5.html#postscreen_dnsbl_sites">postscreen_dnsbl_sites</a> and
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<a href="postconf.5.html#postscreen_dnsbl_threshold">postscreen_dnsbl_threshold</a> parameters).
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<b><a href="postconf.5.html#postscreen_dnsbl_reply_map">postscreen_dnsbl_reply_map</a> (empty)</b>
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A mapping from an actual DNSBL domain name which includes a
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secret password, to the DNSBL domain name that postscreen will
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reply with when it rejects mail.
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<b><a href="postconf.5.html#postscreen_dnsbl_sites">postscreen_dnsbl_sites</a> (empty)</b>
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Optional list of patterns with DNS allow/denylist domains, fil-
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ters and weight factors.
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<b><a href="postconf.5.html#postscreen_dnsbl_threshold">postscreen_dnsbl_threshold</a> (1)</b>
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The inclusive lower bound for blocking a remote SMTP client,
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based on its combined DNSBL score as defined with the
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<a href="postconf.5.html#postscreen_dnsbl_sites">postscreen_dnsbl_sites</a> parameter.
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<b><a href="postconf.5.html#postscreen_greet_action">postscreen_greet_action</a> (ignore)</b>
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The action that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> takes when a remote SMTP client
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speaks before its turn within the time specified with the
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<a href="postconf.5.html#postscreen_greet_wait">postscreen_greet_wait</a> parameter.
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<b><a href="postconf.5.html#postscreen_greet_banner">postscreen_greet_banner</a> ($<a href="postconf.5.html#smtpd_banner">smtpd_banner</a>)</b>
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The <i>text</i> in the optional "220-<i>text</i>..." server response that
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<a href="postscreen.8.html"><b>postscreen</b>(8)</a> sends ahead of the real Postfix SMTP server's "220
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text..." response, in an attempt to confuse bad SMTP clients so
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that they speak before their turn (pre-greet).
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<b><a href="postconf.5.html#postscreen_greet_wait">postscreen_greet_wait</a> (normal: 6s, overload: 2s)</b>
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The amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> will wait for an SMTP
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client to send a command before its turn, and for DNS blocklist
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lookup results to arrive (default: up to 2 seconds under stress,
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up to 6 seconds otherwise).
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<b><a href="postconf.5.html#smtpd_service_name">smtpd_service_name</a> (smtpd)</b>
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The internal service that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> hands off allowed con-
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nections to.
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Available in Postfix version 2.11 and later:
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<b><a href="postconf.5.html#postscreen_dnsbl_whitelist_threshold">postscreen_dnsbl_whitelist_threshold</a> (0)</b>
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Renamed to <a href="postconf.5.html#postscreen_dnsbl_allowlist_threshold">postscreen_dnsbl_allowlist_threshold</a> in Postfix 3.6.
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Available in Postfix version 3.0 and later:
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<b><a href="postconf.5.html#postscreen_dnsbl_timeout">postscreen_dnsbl_timeout</a> (10s)</b>
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The time limit for DNSBL or DNSWL lookups.
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Available in Postfix version 3.6 and later:
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<b><a href="postconf.5.html#postscreen_denylist_action">postscreen_denylist_action</a> (ignore)</b>
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The action that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> takes when a remote SMTP client is
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permanently denylisted with the <a href="postconf.5.html#postscreen_access_list">postscreen_access_list</a> parame-
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ter.
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<b><a href="postconf.5.html#postscreen_allowlist_interfaces">postscreen_allowlist_interfaces</a> (<a href="DATABASE_README.html#types">static</a>:all)</b>
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A list of local <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server IP addresses where a
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non-allowlisted remote SMTP client can obtain <a href="postscreen.8.html"><b>postscreen</b>(8)</a>'s
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temporary allowlist status.
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<b><a href="postconf.5.html#postscreen_dnsbl_allowlist_threshold">postscreen_dnsbl_allowlist_threshold</a> (0)</b>
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Allow a remote SMTP client to skip "before" and "after 220
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greeting" protocol tests, based on its combined DNSBL score as
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defined with the <a href="postconf.5.html#postscreen_dnsbl_sites">postscreen_dnsbl_sites</a> parameter.
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<b><a name="after_220_greeting_tests">AFTER 220 GREETING TESTS</a></b>
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These tests are executed after the remote SMTP client receives the "220
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servername" greeting. If a client passes all tests during this phase,
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it will receive a 4XX response to all RCPT TO commands. After the
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client reconnects, it will be allowed to talk directly to a Postfix
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SMTP server process.
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<b><a href="postconf.5.html#postscreen_bare_newline_action">postscreen_bare_newline_action</a> (ignore)</b>
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The action that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> takes when a remote SMTP client
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sends a bare newline character, that is, a newline not preceded
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by carriage return.
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<b><a href="postconf.5.html#postscreen_bare_newline_enable">postscreen_bare_newline_enable</a> (no)</b>
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Enable "bare newline" SMTP protocol tests in the <a href="postscreen.8.html"><b>postscreen</b>(8)</a>
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server.
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<b><a href="postconf.5.html#postscreen_disable_vrfy_command">postscreen_disable_vrfy_command</a> ($<a href="postconf.5.html#disable_vrfy_command">disable_vrfy_command</a>)</b>
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Disable the SMTP VRFY command in the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> daemon.
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<b><a href="postconf.5.html#postscreen_forbidden_commands">postscreen_forbidden_commands</a> ($<a href="postconf.5.html#smtpd_forbidden_commands">smtpd_forbidden_commands</a>)</b>
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List of commands that the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server considers in vio-
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lation of the SMTP protocol.
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<b><a href="postconf.5.html#postscreen_helo_required">postscreen_helo_required</a> ($<a href="postconf.5.html#smtpd_helo_required">smtpd_helo_required</a>)</b>
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Require that a remote SMTP client sends HELO or EHLO before com-
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mencing a MAIL transaction.
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<b><a href="postconf.5.html#postscreen_non_smtp_command_action">postscreen_non_smtp_command_action</a> (drop)</b>
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The action that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> takes when a remote SMTP client
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sends non-SMTP commands as specified with the <a href="postconf.5.html#postscreen_forbidden_commands">postscreen_forbid</a>-
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<a href="postconf.5.html#postscreen_forbidden_commands">den_commands</a> parameter.
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<b><a href="postconf.5.html#postscreen_non_smtp_command_enable">postscreen_non_smtp_command_enable</a> (no)</b>
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Enable "non-SMTP command" tests in the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server.
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<b><a href="postconf.5.html#postscreen_pipelining_action">postscreen_pipelining_action</a> (enforce)</b>
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The action that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> takes when a remote SMTP client
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sends multiple commands instead of sending one command and wait-
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ing for the server to respond.
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<b><a href="postconf.5.html#postscreen_pipelining_enable">postscreen_pipelining_enable</a> (no)</b>
|
|
Enable "pipelining" SMTP protocol tests in the <a href="postscreen.8.html"><b>postscreen</b>(8)</a>
|
|
server.
|
|
|
|
<b><a name="cache_controls">CACHE CONTROLS</a></b>
|
|
<b><a href="postconf.5.html#postscreen_cache_cleanup_interval">postscreen_cache_cleanup_interval</a> (12h)</b>
|
|
The amount of time between <a href="postscreen.8.html"><b>postscreen</b>(8)</a> cache cleanup runs.
|
|
|
|
<b><a href="postconf.5.html#postscreen_cache_map">postscreen_cache_map</a> (<a href="DATABASE_README.html#types">btree</a>:$<a href="postconf.5.html#data_directory">data_directory</a>/postscreen_cache)</b>
|
|
Persistent storage for the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server decisions.
|
|
|
|
<b><a href="postconf.5.html#postscreen_cache_retention_time">postscreen_cache_retention_time</a> (7d)</b>
|
|
The amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> will cache an expired tem-
|
|
porary allowlist entry before it is removed.
|
|
|
|
<b><a href="postconf.5.html#postscreen_bare_newline_ttl">postscreen_bare_newline_ttl</a> (30d)</b>
|
|
The amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> remembers that a client IP
|
|
address passed a "bare newline" SMTP protocol test, before it
|
|
address is required to pass that test again.
|
|
|
|
<b><a href="postconf.5.html#postscreen_dnsbl_max_ttl">postscreen_dnsbl_max_ttl</a></b>
|
|
<b>(${<a href="postconf.5.html#postscreen_dnsbl_ttl">postscreen_dnsbl_ttl</a>?{$<a href="postconf.5.html#postscreen_dnsbl_ttl">postscreen_dnsbl_ttl</a>}:{1}}h)</b>
|
|
The maximum amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> remembers that a
|
|
client IP address passed a DNS-based reputation test, before it
|
|
is required to pass that test again.
|
|
|
|
<b><a href="postconf.5.html#postscreen_dnsbl_min_ttl">postscreen_dnsbl_min_ttl</a> (60s)</b>
|
|
The minimum amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> remembers that a
|
|
client IP address passed a DNS-based reputation test, before it
|
|
is required to pass that test again.
|
|
|
|
<b><a href="postconf.5.html#postscreen_greet_ttl">postscreen_greet_ttl</a> (1d)</b>
|
|
The amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> remembers that a client IP
|
|
address passed a PREGREET test, before it is required to pass
|
|
that test again.
|
|
|
|
<b><a href="postconf.5.html#postscreen_non_smtp_command_ttl">postscreen_non_smtp_command_ttl</a> (30d)</b>
|
|
The amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> remembers that a client IP
|
|
address passed a "non_smtp_command" SMTP protocol test, before
|
|
it is required to pass that test again.
|
|
|
|
<b><a href="postconf.5.html#postscreen_pipelining_ttl">postscreen_pipelining_ttl</a> (30d)</b>
|
|
The amount of time that <a href="postscreen.8.html"><b>postscreen</b>(8)</a> remembers that a client IP
|
|
address passed a "pipelining" SMTP protocol test, before it is
|
|
required to pass that test again.
|
|
|
|
<b><a name="resource_controls">RESOURCE CONTROLS</a></b>
|
|
<b><a href="postconf.5.html#line_length_limit">line_length_limit</a> (2048)</b>
|
|
Upon input, long lines are chopped up into pieces of at most
|
|
this length; upon delivery, long lines are reconstructed.
|
|
|
|
<b><a href="postconf.5.html#postscreen_client_connection_count_limit">postscreen_client_connection_count_limit</a> ($<a href="postconf.5.html#smtpd_client_connection_count_limit">smtpd_client_connec</a>-</b>
|
|
<b><a href="postconf.5.html#smtpd_client_connection_count_limit">tion_count_limit</a>)</b>
|
|
How many simultaneous connections any remote SMTP client is
|
|
allowed to have with the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> daemon.
|
|
|
|
<b><a href="postconf.5.html#postscreen_command_count_limit">postscreen_command_count_limit</a> (20)</b>
|
|
The limit on the total number of commands per SMTP session for
|
|
<a href="postscreen.8.html"><b>postscreen</b>(8)</a>'s built-in SMTP protocol engine.
|
|
|
|
<b><a href="postconf.5.html#postscreen_command_time_limit">postscreen_command_time_limit</a> (normal: 300s, overload: 10s)</b>
|
|
The time limit to read an entire command line with
|
|
<a href="postscreen.8.html"><b>postscreen</b>(8)</a>'s built-in SMTP protocol engine.
|
|
|
|
<b><a href="postconf.5.html#postscreen_post_queue_limit">postscreen_post_queue_limit</a> ($<a href="postconf.5.html#default_process_limit">default_process_limit</a>)</b>
|
|
The number of clients that can be waiting for service from a
|
|
real Postfix SMTP server process.
|
|
|
|
<b><a href="postconf.5.html#postscreen_pre_queue_limit">postscreen_pre_queue_limit</a> ($<a href="postconf.5.html#default_process_limit">default_process_limit</a>)</b>
|
|
The number of non-allowlisted clients that can be waiting for a
|
|
decision whether they will receive service from a real Postfix
|
|
SMTP server process.
|
|
|
|
<b><a href="postconf.5.html#postscreen_watchdog_timeout">postscreen_watchdog_timeout</a> (10s)</b>
|
|
How much time a <a href="postscreen.8.html"><b>postscreen</b>(8)</a> process may take to respond to a
|
|
remote SMTP client command or to perform a cache operation
|
|
before it is terminated by a built-in watchdog timer.
|
|
|
|
<b><a name="starttls_controls">STARTTLS CONTROLS</a></b>
|
|
<b><a href="postconf.5.html#postscreen_tls_security_level">postscreen_tls_security_level</a> ($<a href="postconf.5.html#smtpd_tls_security_level">smtpd_tls_security_level</a>)</b>
|
|
The SMTP TLS security level for the <a href="postscreen.8.html"><b>postscreen</b>(8)</a> server; when a
|
|
non-empty value is specified, this overrides the obsolete param-
|
|
eters <a href="postconf.5.html#postscreen_use_tls">postscreen_use_tls</a> and <a href="postconf.5.html#postscreen_enforce_tls">postscreen_enforce_tls</a>.
|
|
|
|
<b><a href="postconf.5.html#tlsproxy_service_name">tlsproxy_service_name</a> (tlsproxy)</b>
|
|
The name of the <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> service entry in <a href="master.5.html">master.cf</a>.
|
|
|
|
<b><a name="obsolete_starttls_support_controls">OBSOLETE STARTTLS SUPPORT CONTROLS</a></b>
|
|
These parameters are supported for compatibility with <a href="smtpd.8.html"><b>smtpd</b>(8)</a> legacy
|
|
parameters.
|
|
|
|
<b><a href="postconf.5.html#postscreen_use_tls">postscreen_use_tls</a> ($<a href="postconf.5.html#smtpd_use_tls">smtpd_use_tls</a>)</b>
|
|
Opportunistic TLS: announce STARTTLS support to remote SMTP
|
|
clients, but do not require that clients use TLS encryption.
|
|
|
|
<b><a href="postconf.5.html#postscreen_enforce_tls">postscreen_enforce_tls</a> ($<a href="postconf.5.html#smtpd_enforce_tls">smtpd_enforce_tls</a>)</b>
|
|
Mandatory TLS: announce STARTTLS support to remote SMTP clients,
|
|
and require that clients use TLS encryption.
|
|
|
|
<b><a name="miscellaneous_controls">MISCELLANEOUS CONTROLS</a></b>
|
|
<b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
|
|
The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
|
|
figuration files.
|
|
|
|
<b><a href="postconf.5.html#delay_logging_resolution_limit">delay_logging_resolution_limit</a> (2)</b>
|
|
The maximal number of digits after the decimal point when log-
|
|
ging sub-second delay values.
|
|
|
|
<b><a href="postconf.5.html#command_directory">command_directory</a> (see 'postconf -d' output)</b>
|
|
The location of all postfix administrative commands.
|
|
|
|
<b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b>
|
|
The maximum amount of time that an idle Postfix daemon process
|
|
waits for an incoming connection before terminating voluntarily.
|
|
|
|
<b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
|
|
The process ID of a Postfix command or daemon process.
|
|
|
|
<b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b>
|
|
The process name of a Postfix command or daemon process.
|
|
|
|
<b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
|
|
The syslog facility of Postfix logging.
|
|
|
|
<b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
|
|
A prefix that is prepended to the process name in syslog
|
|
records, so that, for example, "smtpd" becomes "prefix/smtpd".
|
|
|
|
Available in Postfix 3.3 and later:
|
|
|
|
<b><a href="postconf.5.html#service_name">service_name</a> (read-only)</b>
|
|
The <a href="master.5.html">master.cf</a> service name of a Postfix daemon process.
|
|
|
|
Available in Postfix 3.5 and later:
|
|
|
|
<b><a href="postconf.5.html#info_log_address_format">info_log_address_format</a> (external)</b>
|
|
The email address form that will be used in non-debug logging
|
|
(info, warning, etc.).
|
|
|
|
<b><a name="see_also">SEE ALSO</a></b>
|
|
<a href="smtpd.8.html">smtpd(8)</a>, Postfix SMTP server
|
|
<a href="tlsproxy.8.html">tlsproxy(8)</a>, Postfix TLS proxy server
|
|
<a href="dnsblog.8.html">dnsblog(8)</a>, DNS allow/denylist logger
|
|
<a href="postlogd.8.html">postlogd(8)</a>, Postfix logging
|
|
syslogd(8), system logging
|
|
|
|
<b><a name="readme_files">README FILES</a></b>
|
|
<a href="POSTSCREEN_README.html">POSTSCREEN_README</a>, Postfix Postscreen Howto
|
|
|
|
<b><a name="license">LICENSE</a></b>
|
|
The Secure Mailer license must be distributed with this software.
|
|
|
|
<b><a name="history">HISTORY</a></b>
|
|
This service was introduced with Postfix version 2.8.
|
|
|
|
Many ideas in <a href="postscreen.8.html"><b>postscreen</b>(8)</a> were explored in earlier work by Michael
|
|
Tokarev, in OpenBSD spamd, and in MailChannels Traffic Control.
|
|
|
|
<b>AUTHOR(S)</b>
|
|
Wietse Venema
|
|
IBM T.J. Watson Research
|
|
P.O. Box 704
|
|
Yorktown Heights, NY 10598, USA
|
|
|
|
Wietse Venema
|
|
Google, Inc.
|
|
111 8th Avenue
|
|
New York, NY 10011, USA
|
|
|
|
POSTSCREEN(8)
|
|
</pre> </body> </html>
|