242 lines
14 KiB
HTML
242 lines
14 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 - verify(8) </title>
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</head> <body> <pre>
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VERIFY(8) VERIFY(8)
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<b><a name="name">NAME</a></b>
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verify - Postfix address verification server
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<b><a name="synopsis">SYNOPSIS</a></b>
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<b>verify</b> [generic Postfix daemon options]
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<b><a name="description">DESCRIPTION</a></b>
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The <a href="verify.8.html"><b>verify</b>(8)</a> address verification server maintains a record of what
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recipient addresses are known to be deliverable or undeliverable.
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Addresses are verified by injecting probe messages into the Postfix
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queue. Probe messages are run through all the routing and rewriting
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machinery except for final delivery, and are discarded rather than
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being deferred or bounced.
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Address verification relies on the answer from the nearest MTA for the
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specified address, and will therefore not detect all undeliverable
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addresses.
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The <a href="verify.8.html"><b>verify</b>(8)</a> server is designed to run under control by the Postfix
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master server. It maintains an optional persistent database. To avoid
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being interrupted by "postfix stop" in the middle of a database update,
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the process runs in a separate process group.
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The <a href="verify.8.html"><b>verify</b>(8)</a> server implements the following requests:
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<b>update</b> <i>address status text</i>
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Update the status and text of the specified address.
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<b>query</b> <i>address</i>
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Look up the <i>status</i> and <i>text</i> for the specified <i>address</i>. If the
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status is unknown, a probe is sent and an "in progress" status
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is returned.
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<b><a name="security">SECURITY</a></b>
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The address verification server is not security-sensitive. It does not
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talk to the network, and it does not talk to local users. The verify
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server can run chrooted at fixed low privilege.
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The address verification server can be coerced to store unlimited
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amounts of garbage. Limiting the cache expiry time trades one problem
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(disk space exhaustion) for another one (poor response time to client
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requests).
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With Postfix version 2.5 and later, the <a href="verify.8.html"><b>verify</b>(8)</a> server no longer uses
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root privileges when opening the <b><a href="postconf.5.html#address_verify_map">address_verify_map</a></b> cache file. The
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file should now be stored under the Postfix-owned <b><a href="postconf.5.html#data_directory">data_directory</a></b>. As a
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migration aid, an attempt to open a cache file under a non-Postfix
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directory is redirected to the Postfix-owned <b><a href="postconf.5.html#data_directory">data_directory</a></b>, and a
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warning is logged.
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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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Address verification probe messages add additional traffic to the mail
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queue. Recipient verification may cause an increased load on
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down-stream servers in the case of a dictionary attack or a flood of
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backscatter bounces. Sender address verification may cause your site
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to be denylisted by some providers.
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If the persistent database ever gets corrupted then the world comes to
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an end and human intervention is needed. This violates a basic Postfix
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principle.
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<b><a name="configuration_parameters">CONFIGURATION PARAMETERS</a></b>
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Changes to <a href="postconf.5.html"><b>main.cf</b></a> are not picked up automatically, as <a href="verify.8.html"><b>verify</b>(8)</a> pro-
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cesses are long-lived. Use the command "<b>postfix reload</b>" after a config-
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uration 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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<b><a name="probe_message_controls">PROBE MESSAGE CONTROLS</a></b>
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<b><a href="postconf.5.html#address_verify_sender">address_verify_sender</a> ($<a href="postconf.5.html#double_bounce_sender">double_bounce_sender</a>)</b>
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The sender address to use in address verification probes; prior
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to Postfix 2.5 the default was "postmaster".
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Available with Postfix 2.9 and later:
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<b><a href="postconf.5.html#address_verify_sender_ttl">address_verify_sender_ttl</a> (0s)</b>
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The time between changes in the time-dependent portion of
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address verification probe sender addresses.
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<b><a name="cache_controls">CACHE CONTROLS</a></b>
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<b><a href="postconf.5.html#address_verify_map">address_verify_map</a> (see 'postconf -d' output)</b>
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Lookup table for persistent address verification status storage.
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<b><a href="postconf.5.html#address_verify_positive_expire_time">address_verify_positive_expire_time</a> (31d)</b>
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The time after which a successful probe expires from the address
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verification cache.
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<b><a href="postconf.5.html#address_verify_positive_refresh_time">address_verify_positive_refresh_time</a> (7d)</b>
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The time after which a successful address verification probe
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needs to be refreshed.
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<b><a href="postconf.5.html#address_verify_negative_cache">address_verify_negative_cache</a> (yes)</b>
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Enable caching of failed address verification probe results.
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<b><a href="postconf.5.html#address_verify_negative_expire_time">address_verify_negative_expire_time</a> (3d)</b>
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The time after which a failed probe expires from the address
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verification cache.
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<b><a href="postconf.5.html#address_verify_negative_refresh_time">address_verify_negative_refresh_time</a> (3h)</b>
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The time after which a failed address verification probe needs
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to be refreshed.
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Available with Postfix 2.7 and later:
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<b><a href="postconf.5.html#address_verify_cache_cleanup_interval">address_verify_cache_cleanup_interval</a> (12h)</b>
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The amount of time between <a href="verify.8.html"><b>verify</b>(8)</a> address verification data-
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base cleanup runs.
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<b><a name="probe_message_routing_controls">PROBE MESSAGE ROUTING CONTROLS</a></b>
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By default, probe messages are delivered via the same route as regular
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messages. The following parameters can be used to override specific
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message routing mechanisms.
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<b><a href="postconf.5.html#address_verify_relayhost">address_verify_relayhost</a> ($<a href="postconf.5.html#relayhost">relayhost</a>)</b>
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Overrides the <a href="postconf.5.html#relayhost">relayhost</a> parameter setting for address verifica-
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tion probes.
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<b><a href="postconf.5.html#address_verify_transport_maps">address_verify_transport_maps</a> ($<a href="postconf.5.html#transport_maps">transport_maps</a>)</b>
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Overrides the <a href="postconf.5.html#transport_maps">transport_maps</a> parameter setting for address veri-
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fication probes.
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<b><a href="postconf.5.html#address_verify_local_transport">address_verify_local_transport</a> ($<a href="postconf.5.html#local_transport">local_transport</a>)</b>
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Overrides the <a href="postconf.5.html#local_transport">local_transport</a> parameter setting for address ver-
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ification probes.
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<b><a href="postconf.5.html#address_verify_virtual_transport">address_verify_virtual_transport</a> ($<a href="postconf.5.html#virtual_transport">virtual_transport</a>)</b>
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Overrides the <a href="postconf.5.html#virtual_transport">virtual_transport</a> parameter setting for address
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verification probes.
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<b><a href="postconf.5.html#address_verify_relay_transport">address_verify_relay_transport</a> ($<a href="postconf.5.html#relay_transport">relay_transport</a>)</b>
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Overrides the <a href="postconf.5.html#relay_transport">relay_transport</a> parameter setting for address ver-
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ification probes.
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<b><a href="postconf.5.html#address_verify_default_transport">address_verify_default_transport</a> ($<a href="postconf.5.html#default_transport">default_transport</a>)</b>
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Overrides the <a href="postconf.5.html#default_transport">default_transport</a> parameter setting for address
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verification probes.
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Available in Postfix 2.3 and later:
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<b><a href="postconf.5.html#address_verify_sender_dependent_relayhost_maps">address_verify_sender_dependent_relayhost_maps</a> ($<a href="postconf.5.html#sender_dependent_relayhost_maps">sender_depen</a>-</b>
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<b><a href="postconf.5.html#sender_dependent_relayhost_maps">dent_relayhost_maps</a>)</b>
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Overrides the <a href="postconf.5.html#sender_dependent_relayhost_maps">sender_dependent_relayhost_maps</a> parameter setting
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for address verification probes.
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Available in Postfix 2.7 and later:
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<b><a href="postconf.5.html#address_verify_sender_dependent_default_transport_maps">address_verify_sender_dependent_default_transport_maps</a> ($<a href="postconf.5.html#sender_dependent_default_transport_maps">sender_depen</a>-</b>
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<b><a href="postconf.5.html#sender_dependent_default_transport_maps">dent_default_transport_maps</a>)</b>
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Overrides the <a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default_transport_maps</a> parameter
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setting for address verification probes.
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<b><a name="smtputf8_controls">SMTPUTF8 CONTROLS</a></b>
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Preliminary SMTPUTF8 support is introduced with Postfix 3.0.
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<b><a href="postconf.5.html#smtputf8_autodetect_classes">smtputf8_autodetect_classes</a> (sendmail, verify)</b>
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Detect that a message requires SMTPUTF8 support for the speci-
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fied mail origin classes.
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Available in Postfix version 3.2 and later:
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<b><a href="postconf.5.html#enable_idna2003_compatibility">enable_idna2003_compatibility</a> (no)</b>
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Enable 'transitional' compatibility between IDNA2003 and
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IDNA2008, when converting UTF-8 domain names to/from the ASCII
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form that is used for DNS lookups.
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<b><a name="miscellaneous_controls">MISCELLANEOUS CONTROLS</a></b>
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<b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
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The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
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figuration files.
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<b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b>
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How much time a Postfix daemon process may take to handle a
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request before it is terminated by a built-in watchdog timer.
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<b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b>
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The time limit for sending or receiving information over an
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internal communication channel.
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<b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
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The process ID of a Postfix command or daemon process.
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<b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b>
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The process name of a Postfix command or daemon process.
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<b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b>
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The location of the Postfix top-level queue directory.
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<b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
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The syslog facility of Postfix logging.
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<b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
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A prefix that is prepended to the process name in syslog
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records, so that, for example, "smtpd" becomes "prefix/smtpd".
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Available in Postfix 3.3 and later:
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<b><a href="postconf.5.html#service_name">service_name</a> (read-only)</b>
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The <a href="master.5.html">master.cf</a> service name of a Postfix daemon process.
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<b><a name="see_also">SEE ALSO</a></b>
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<a href="smtpd.8.html">smtpd(8)</a>, Postfix SMTP server
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<a href="cleanup.8.html">cleanup(8)</a>, enqueue Postfix message
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<a href="postconf.5.html">postconf(5)</a>, configuration parameters
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<a href="postlogd.8.html">postlogd(8)</a>, Postfix logging
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syslogd(8), system logging
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<b><a name="readme_files">README FILES</a></b>
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<a href="ADDRESS_VERIFICATION_README.html">ADDRESS_VERIFICATION_README</a>, address verification howto
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<b><a name="license">LICENSE</a></b>
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The Secure Mailer license must be distributed with this software.
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<b><a name="history">HISTORY</a></b>
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This service was introduced with Postfix version 2.1.
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<b>AUTHOR(S)</b>
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Wietse Venema
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IBM T.J. Watson Research
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P.O. Box 704
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Yorktown Heights, NY 10598, USA
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Wietse Venema
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Google, Inc.
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111 8th Avenue
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New York, NY 10011, USA
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VERIFY(8)
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</pre> </body> </html>
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