229 lines
10 KiB
HTML
229 lines
10 KiB
HTML
<html> <head> </head> <body> <pre>
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VIRTUAL(8) VIRTUAL(8)
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<b>NAME</b>
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virtual - Postfix virtual domain mail delivery agent
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<b>SYNOPSIS</b>
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<b>virtual</b> [generic Postfix daemon options]
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<b>DESCRIPTION</b>
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The <b>virtual</b> delivery agent is designed for virtual mail
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hosting services. Originally based on the Postfix local
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delivery agent, this agent looks up recipients with map
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lookups of their full recipient address, instead of using
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hard-coded unix password file lookups of the address local
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part only.
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This delivery agent only delivers mail. Other features
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such as mail forwarding, out-of-office notifications,
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etc., must be configured via virtual maps or via similar
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lookup mechanisms.
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<b>MAILBOX</b> <b>LOCATION</b>
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The mailbox location is controlled by the <b>virtual</b><i>_</i><b>mail-</b>
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<b>box</b><i>_</i><b>base</b> and <b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>maps</b> configuration parameters
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(see below). The <b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>maps</b> table is indexed by
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the full recipient address.
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The mailbox pathname is constructed as follows:
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<b>$virtual</b><i>_</i><b>mailbox</b><i>_</i><b>base/$virtual</b><i>_</i><b>mailbox</b><i>_</i><b>maps(</b><i>recipient</i><b>)</b>
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where <i>recipient</i> is the full recipient address.
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<b>UNIX</b> <b>MAILBOX</b> <b>FORMAT</b>
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When the mailbox location does not end in <b>/</b>, the message
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is delivered in UNIX mailbox format. This format stores
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multiple messages in one textfile.
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The <b>virtual</b> delivery agent prepends a "<b>From</b> <i>sender</i>
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<i>time_stamp</i>" envelope header to each message, prepends a
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<b>Delivered-To:</b> message header with the envelope recipient
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address, prepends a <b>Return-Path:</b> message header with the
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envelope sender address, prepends a > character to lines
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beginning with "<b>From</b> ", and appends an empty line.
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The mailbox is locked for exclusive access while delivery
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is in progress. In case of problems, an attempt is made to
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truncate the mailbox to its original length.
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<b>QMAIL</b> <b>MAILDIR</b> <b>FORMAT</b>
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When the mailbox location ends in <b>/</b>, the message is deliv-
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ered in qmail <b>maildir</b> format. This format stores one mes-
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sage per file.
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The <b>virtual</b> delivery agent daemon prepends a <b>Delivered-To:</b>
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message header with the envelope recipient address and
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prepends a <b>Return-Path:</b> message header with the envelope
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sender address.
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By definition, <b>maildir</b> format does not require file lock-
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ing during mail delivery or retrieval.
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<b>MAILBOX</b> <b>OWNERSHIP</b>
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Mailbox ownership is controlled by the <b>virtual</b><i>_</i><b>uid</b><i>_</i><b>maps</b>
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and <b>virtual</b><i>_</i><b>gid</b><i>_</i><b>maps</b> lookup tables, which are indexed with
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the full recipient address. Each table provides a string
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with the numerical user and group ID, respectively.
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The <b>virtual</b><i>_</i><b>minimum</b><i>_</i><b>uid</b> parameter imposes a lower bound on
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numerical user ID values that may be specified in any <b>vir-</b>
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<b>tual</b><i>_</i><b>owner</b><i>_</i><b>maps</b> or <b>virtual</b><i>_</i><b>uid</b><i>_</i><b>maps</b>.
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<b>SECURITY</b>
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The virtual delivery agent is not security sensitive, pro-
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vided that the lookup tables with recipient user/group ID
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information are adequately protected. This program is not
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designed to run chrooted.
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<b>STANDARDS</b>
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<a href="http://www.faqs.org/rfcs/rfc822.html">RFC 822</a> (ARPA Internet Text Messages)
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<b>DIAGNOSTICS</b>
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Mail bounces when the recipient has no mailbox or when the
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recipient is over disk quota. In all other cases, mail for
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an existing recipient is deferred and a warning is logged.
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Problems and transactions are logged to <b>syslogd</b>(8). Cor-
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rupted message files are marked so that the queue manager
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can move them to the <b>corrupt</b> queue afterwards.
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Depending on the setting of the <b>notify</b><i>_</i><b>classes</b> parameter,
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the postmaster is notified of bounces and of other trou-
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ble.
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<b>BUGS</b>
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This delivery agent silently ignores address extensions.
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Postfix should have lookup tables that can return multiple
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result attributes. In order to avoid the inconvenience of
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maintaining three tables, use an LDAP or MYSQL database.
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<b>CONFIGURATION</b> <b>PARAMETERS</b>
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The following <b>main.cf</b> parameters are especially relevant
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to this program. See the Postfix <b>main.cf</b> file for syntax
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details and for default values. Use the <b>postfix</b> <b>reload</b>
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command after a configuration change.
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<b>Mailbox</b> <b>delivery</b>
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<b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>base</b>
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Specifies a path that is prepended to all mailbox
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or maildir paths. This is a safety measure to
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ensure that an out of control map in <b>virtual</b><i>_</i><b>mail-</b>
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<b>box</b><i>_</i><b>maps</b> doesn't litter the filesystem with mail-
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boxes. While it could be set to "/", this setting
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isn't recommended.
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<b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>maps</b> (regexp maps disallowed)
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Recipients are looked up in these maps to determine
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the path to their mailbox or maildir. If the
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returned path ends in a slash ("/"), maildir-style
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delivery is carried out, otherwise the path is
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assumed to specify a UNIX-style mailbox file.
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Note that <b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>base</b> is unconditionally
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prepended to this path.
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<b>virtual</b><i>_</i><b>minimum</b><i>_</i><b>uid</b>
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Specifies a minimum uid that will be accepted as a
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return from a <b>virtual</b><i>_</i><b>owner</b><i>_</i><b>maps</b> or <b>vir-</b>
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<b>tual</b><i>_</i><b>uid</b><i>_</i><b>maps</b> lookup. Returned values less than
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this will be rejected, and the message will be
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deferred.
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<b>virtual</b><i>_</i><b>uid</b><i>_</i><b>maps</b> (regexp maps disallowed)
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Recipients are looked up in these maps to determine
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the user ID to be used when writing to the target
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mailbox.
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<b>virtual</b><i>_</i><b>gid</b><i>_</i><b>maps</b> (regexp maps disallowed)
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Recipients are looked up in these maps to determine
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the group ID to be used when writing to the target
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mailbox.
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<b>Locking</b> <b>controls</b>
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<b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>lock</b>
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How to lock UNIX-style mailboxes: one or more of
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<b>flock</b>, <b>fcntl</b> or <b>dotlock</b>. The <b>dotlock</b> method
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requires that the recipient UID or GID has write
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access to the parent directory of the mailbox file.
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This setting is ignored with <b>maildir</b> style deliv-
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ery, because such deliveries are safe without
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explicit locks.
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Use the command <b>postconf</b> <b>-l</b> to find out what lock-
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ing methods are available on your system.
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<b>deliver</b><i>_</i><b>lock</b><i>_</i><b>attempts</b>
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Limit the number of attempts to acquire an exclu-
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sive lock on a UNIX-style mailbox file.
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<b>deliver</b><i>_</i><b>lock</b><i>_</i><b>delay</b>
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Time (default: seconds) between successive attempts
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to acquire an exclusive lock on a UNIX-style mail-
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box file. The actual delay is slightly randomized.
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<b>stale</b><i>_</i><b>lock</b><i>_</i><b>time</b>
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Limit the time after which a stale lockfile is
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removed (applicable to UNIX-style mailboxes only).
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<b>Resource</b> <b>controls</b>
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<b>virtual</b><i>_</i><b>destination</b><i>_</i><b>concurrency</b><i>_</i><b>limit</b>
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Limit the number of parallel deliveries to the same
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domain via the <b>virtual</b> delivery agent. The default
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limit is taken from the <b>default</b><i>_</i><b>destination</b><i>_</i><b>concur-</b>
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<b>rency</b><i>_</i><b>limit</b> parameter. The limit is enforced by
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the Postfix queue manager.
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<b>virtual</b><i>_</i><b>destination</b><i>_</i><b>recipient</b><i>_</i><b>limit</b>
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Limit the number of recipients per message delivery
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via the <b>virtual</b> delivery agent. The default limit
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is taken from the <b>default</b><i>_</i><b>destination</b><i>_</i><b>recipi-</b>
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<b>ent</b><i>_</i><b>limit</b> parameter. The limit is enforced by the
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Postfix queue manager.
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<b>virtual</b><i>_</i><b>mailbox</b><i>_</i><b>limit</b>
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The maximal size in bytes of a mailbox or maildir
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file. Set to zero to disable the limit.
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<b>HISTORY</b>
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This agent was originally based on the Postfix local
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delivery agent. Modifications mainly consisted of removing
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code that either was not applicable or that was not safe
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in this context: aliases, ~user/.forward files, delivery
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to "|command" or to /file/name.
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The <b>Delivered-To:</b> header appears in the <b>qmail</b> system by
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Daniel Bernstein.
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The <b>maildir</b> structure appears in the <b>qmail</b> system by
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Daniel Bernstein.
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<b>SEE</b> <b>ALSO</b>
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<a href="bounce.8.html">bounce(8)</a> non-delivery status reports
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syslogd(8) system logging
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<a href="qmgr.8.html">qmgr(8)</a> queue manager
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<b>LICENSE</b>
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The Secure Mailer license must be distributed with this
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software.
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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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Andrew McNamara
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andrewm@connect.com.au
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connect.com.au Pty. Ltd.
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Level 3, 213 Miller St
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North Sydney 2060, NSW, Australia
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</pre> </body> </html>
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