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verify [generic Postfix daemon options]
Addresses are verified by injecting probe messages into the Postfix queue. Probe messages are run through all the routing and rewriting machinery except for final delivery, and are discarded rather than being deferred or bounced.
Address verification relies on the answer from the nearest MTA for the specified address, and will therefore not detect all undeliverable addresses.
The verify(8) server is designed to run under control by the Postfix master server. It maintains an optional persistent database. To avoid being interrupted by "postfix stop" in the middle of a database update, the process runs in a separate process group.
The verify(8) server implements the following requests:
|update address status text||Update the status and text of the specified address.|
|query address||Look up the status and text for the specified address. If the status is unknown, a probe is sent and an "in progress" status is returned.|
The address verification server can be coerced to store unlimited amounts of garbage. Limiting the cache size trades one problem (disk space exhaustion) for another one (poor response time to client requests).
If the persistent database ever gets corrupted then the world comes to an end and human intervention is needed. This violates a basic Postfix principle.
The text below provides only a parameter summary. See postconf(5) for more details including examples.
|address_verify_map (empty)||Optional lookup table for persistent address verification status storage.|
|address_verify_sender (postmaster)||The sender address to use in address verification probes.|
|address_verify_positive_expire_time (31d)||The time after which a successful probe expires from the address verification cache.|
|address_verify_positive_refresh_time (7d)||The time after which a successful address verification probe needs to be refreshed.|
|address_verify_negative_cache (yes)||Enable caching of failed address verification probe results.|
|address_verify_negative_expire_time (3d)||The time after which a failed probe expires from the address verification cache.|
|address_verify_negative_refresh_time (3h)||The time after which a failed address verification probe needs to be refreshed.|
|address_verify_relayhost ($relayhost)||Overrides the relayhost parameter setting for address verification probes.|
|address_verify_transport_maps ($transport_maps)||Overrides the transport_maps parameter setting for address verification probes.|
|address_verify_local_transport ($local_transport)||Overrides the local_transport parameter setting for address verification probes.|
|address_verify_virtual_transport ($virtual_transport)||Overrides the virtual_transport parameter setting for address verification probes.|
|address_verify_relay_transport ($relay_transport)||Overrides the relay_transport parameter setting for address verification probes.|
|address_verify_default_transport ($default_transport)||Overrides the default_transport parameter setting for address verification probes.|
|config_directory (see postconf -d output)||The default location of the Postfix main.cf and master.cf configuration files.|
|daemon_timeout (18000s)||How much time a Postfix daemon process may take to handle a request before it is terminated by a built-in watchdog timer.|
|ipc_timeout (3600s)||The time limit for sending or receiving information over an internal communication channel.|
|process_id (read-only)||The process ID of a Postfix command or daemon process.|
|process_name (read-only)||The process name of a Postfix command or daemon process.|
|queue_directory (see postconf -d output)||The location of the Postfix top-level queue directory.|
|syslog_facility (mail)||The syslog facility of Postfix logging.|
|syslog_name (postfix)||The mail system name that is prepended to the process name in syslog records, so that "smtpd" becomes, for example, "postfix/smtpd".|
smtpd(8), Postfix SMTP server cleanup(8), enqueue Postfix message postconf(5), configuration parameters syslogd(5), system logging
ADDRESS_VERIFICATION_README, address verification howto
Wietse Venema IBM T.J. Watson Research P.O. Box 704 Yorktown Heights, NY 10598, USA
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