7
Postfix address verification server
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\fBverify\fR [generic Postfix daemon options]
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The Postfix address verification server maintains a record
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of what recipient addresses are known to be deliverable or
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Addresses are verified by injecting probe messages into the
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Postfix queue. Probe messages are run through all the routing
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and rewriting machinery except for final delivery, and are
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discarded rather than being deferred or bounced.
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Address verification relies on the answer from the nearest
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MTA for the specified address, and will therefore not detect
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all undeliverable addresses.
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This server is designed to run under control by the Postfix
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master server. It maintains an optional persistent database.
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To avoid being interrupted by "postfix stop" in the middle
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of a database update, the process runs in a separate process
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This server implements the following requests:
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.IP "\fBupdate\fI address status text\fR"
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Update the status and text of the specified address.
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.IP "\fBquery\fI address\fR"
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Look up the \fIstatus\fR and \fItext\fR for the specified address.
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If the status is unknown, a probe is sent and an "in progress"
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The address verification server is not security-sensitive. It does
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not talk to the network, and it does not talk to local users.
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The verify server can run chrooted at fixed low privilege.
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The address verification server can be coerced to store
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unlimited amounts of garbage. Limiting the cache size
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trades one problem (disk space exhaustion) for another
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one (poor response time to client requests).
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Problems and transactions are logged to \fBsyslogd\fR(8).
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The address verification service is suitable only for sites that
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handle a low mail volume. Verification probes add additional
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traffic to the mail queue and perform poorly under high load.
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Servers may blacklist sites that probe excessively, or that
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probe excessively for non-existent recipient addresses.
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If the persistent database ever gets corrupted then the world
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comes to an end and human intervention is needed. This violates
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a basic Postfix principle.
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.SH "CONFIGURATION PARAMETERS"
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Changes to \fBmain.cf\fR are not picked up automatically, as verify(8)
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processes are persistent. Use the command "\fBpostfix reload\fR" after
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a configuration change.
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The text below provides only a parameter summary. See
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postconf(5) for more details including examples.
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.IP "\fBaddress_verify_map (empty)\fR"
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Optional lookup table for persistent address verification status
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.IP "\fBaddress_verify_sender (postmaster)\fR"
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The sender address to use in address verification probes.
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.IP "\fBaddress_verify_positive_expire_time (31d)\fR"
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The time after which a successful probe expires from the address
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.IP "\fBaddress_verify_positive_refresh_time (7d)\fR"
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The time after which a successful address verification probe needs
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.IP "\fBaddress_verify_negative_cache (yes)\fR"
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Enable caching of failed address verification probe results.
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.IP "\fBaddress_verify_negative_expire_time (3d)\fR"
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The time after which a failed probe expires from the address
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.IP "\fBaddress_verify_negative_refresh_time (3h)\fR"
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The time after which a failed address verification probe needs to
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.SH "PROBE MESSAGE ROUTING CONTROLS"
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By default, probe messages are delivered via the same route
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as regular messages. The following parameters can be used to
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override specific message routing mechanisms.
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.IP "\fBaddress_verify_relayhost ($relayhost)\fR"
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Overrides the relayhost parameter setting for address verification
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.IP "\fBaddress_verify_transport_maps ($transport_maps)\fR"
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Overrides the transport_maps parameter setting for address verification
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.IP "\fBaddress_verify_local_transport ($local_transport)\fR"
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Overrides the local_transport parameter setting for address
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.IP "\fBaddress_verify_virtual_transport ($virtual_transport)\fR"
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Overrides the virtual_transport parameter setting for address
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.IP "\fBaddress_verify_relay_transport ($relay_transport)\fR"
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Overrides the relay_transport parameter setting for address
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.IP "\fBaddress_verify_default_transport ($default_transport)\fR"
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Overrides the default_transport parameter setting for address
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.SH "MISCELLANEOUS CONTROLS"
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.IP "\fBconfig_directory (see 'postconf -d' output)\fR"
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The default location of the Postfix main.cf and master.cf
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.IP "\fBdaemon_timeout (18000s)\fR"
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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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.IP "\fBipc_timeout (3600s)\fR"
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The time limit for sending or receiving information over an internal
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communication channel.
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.IP "\fBprocess_id (read-only)\fR"
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The process ID of a Postfix command or daemon process.
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.IP "\fBprocess_name (read-only)\fR"
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The process name of a Postfix command or daemon process.
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.IP "\fBqueue_directory (see 'postconf -d' output)\fR"
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The location of the Postfix top-level queue directory.
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.IP "\fBsyslog_facility (mail)\fR"
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The syslog facility of Postfix logging.
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.IP "\fBsyslog_name (postfix)\fR"
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The mail system name that is prepended to the process name in syslog
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records, so that "smtpd" becomes, for example, "postfix/smtpd".
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smtpd(8), Postfix SMTP server
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cleanup(8), enqueue Postfix message
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postconf(5), configuration parameters
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syslogd(5), system logging
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Use "\fBpostconf readme_directory\fR" or
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"\fBpostconf html_directory\fR" to locate this information.
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ADDRESS_VERIFICATION_README, address verification howto
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The Secure Mailer license must be distributed with this software.
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This service was introduced with Postfix version 2.1.
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IBM T.J. Watson Research
191
Yorktown Heights, NY 10598, USA
added
removed
man/man8/verify.8
