1VERIFY(8) System Manager's Manual VERIFY(8)
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6 verify - Postfix address verification server
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9 verify [generic Postfix daemon options]
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12 The verify(8) address verification server maintains a record of what
13 recipient addresses are known to be deliverable or undeliverable.
14 Addresses are verified by injecting probe messages into the Postfix
16 queue. Probe messages are run through all the routing and rewriting
17 machinery except for final delivery, and are discarded rather than
18 being deferred or bounced.
19 Address verification relies on the answer from the nearest MTA for the
21 specified address, and will therefore not detect all undeliverable
22 addresses.
23 The verify(8) server is designed to run under control by the Postfix
25 master server. It maintains an optional persistent database. To avoid
26 being interrupted by "postfix stop" in the middle of a database update,
27 the process runs in a separate process group.
28 The verify(8) server implements the following requests:
30 update address status text
32 Update the status and text of the specified address.
33 query address
35 Look up the status and text for the specified address. If the
36 status is unknown, a probe is sent and an "in progress" status
37 is returned.
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40 The address verification server is not security-sensitive. It does not
41 talk to the network, and it does not talk to local users. The verify
42 server can run chrooted at fixed low privilege.
43 The address verification server can be coerced to store unlimited
45 amounts of garbage. Limiting the cache size trades one problem (disk
46 space exhaustion) for another one (poor response time to client
47 requests).
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50 Problems and transactions are logged to syslogd(8).
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53 The address verification service is suitable only for sites that handle
54 a low mail volume. Verification probes add additional traffic to the
55 mail queue and perform poorly under high load. Servers may blacklist
56 sites that probe excessively, or that probe excessively for non-exis‐
57 tent recipient addresses.
58 If the persistent database ever gets corrupted then the world comes to
60 an end and human intervention is needed. This violates a basic Postfix
61 principle.
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64 Changes to main.cf are not picked up automatically, as verify(8) pro‐
65 cesses are persistent. Use the command "postfix reload" after a config‐
66 uration change.
67 The text below provides only a parameter summary. See postconf(5) for
69 more details including examples.
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72 address_verify_map (empty)
73 Optional lookup table for persistent address verification status
74 storage.
75 address_verify_sender (postmaster)
77 The sender address to use in address verification probes.
78 address_verify_positive_expire_time (31d)
80 The time after which a successful probe expires from the address
81 verification cache.
82 address_verify_positive_refresh_time (7d)
84 The time after which a successful address verification probe
85 needs to be refreshed.
86 address_verify_negative_cache (yes)
88 Enable caching of failed address verification probe results.
89 address_verify_negative_expire_time (3d)
91 The time after which a failed probe expires from the address
92 verification cache.
93 address_verify_negative_refresh_time (3h)
95 The time after which a failed address verification probe needs
96 to be refreshed.
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99 By default, probe messages are delivered via the same route as regular
100 messages. The following parameters can be used to override specific
101 message routing mechanisms.
102 address_verify_relayhost ($relayhost)
104 Overrides the relayhost parameter setting for address verifica‐
105 tion probes.
106 address_verify_transport_maps ($transport_maps)
108 Overrides the transport_maps parameter setting for address veri‐
109 fication probes.
110 address_verify_local_transport ($local_transport)
112 Overrides the local_transport parameter setting for address ver‐
113 ification probes.
114 address_verify_virtual_transport ($virtual_transport)
116 Overrides the virtual_transport parameter setting for address
117 verification probes.
118 address_verify_relay_transport ($relay_transport)
120 Overrides the relay_transport parameter setting for address ver‐
121 ification probes.
122 address_verify_default_transport ($default_transport)
124 Overrides the default_transport parameter setting for address
125 verification probes.
126
128 config_directory (see 'postconf -d' output)
129 The default location of the Postfix main.cf and master.cf con‐
130 figuration files.
131 daemon_timeout (18000s)
133 How much time a Postfix daemon process may take to handle a
134 request before it is terminated by a built-in watchdog timer.
135 ipc_timeout (3600s)
137 The time limit for sending or receiving information over an
138 internal communication channel.
139 process_id (read-only)
141 The process ID of a Postfix command or daemon process.
142 process_name (read-only)
144 The process name of a Postfix command or daemon process.
145 queue_directory (see 'postconf -d' output)
147 The location of the Postfix top-level queue directory.
148 syslog_facility (mail)
150 The syslog facility of Postfix logging.
151 syslog_name (postfix)
153 The mail system name that is prepended to the process name in
154 syslog records, so that "smtpd" becomes, for example, "post‐
155 fix/smtpd".
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158 smtpd(8), Postfix SMTP server
159 cleanup(8), enqueue Postfix message
160 postconf(5), configuration parameters
161 syslogd(5), system logging
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164 Use "postconf readme_directory" or "postconf html_directory" to locate
165 this information.
166 ADDRESS_VERIFICATION_README, address verification howto
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169 The Secure Mailer license must be distributed with this software.
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172 This service was introduced with Postfix version 2.1.
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175 Wietse Venema
176 IBM T.J. Watson Research
177 P.O. Box 704
178 Yorktown Heights, NY 10598, USA
179 VERIFY(8)