1<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3<html> <head> 4<meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> 5<title> Postfix manual - verify(8) </title> 6</head> <body> <pre> 7VERIFY(8) VERIFY(8) 8 9<b>NAME</b> 10 verify - Postfix address verification server 11 12<b>SYNOPSIS</b> 13 <b>verify</b> [generic Postfix daemon options] 14 15<b>DESCRIPTION</b> 16 The <a href="verify.8.html"><b>verify</b>(8)</a> address verification server maintains a 17 record of what recipient addresses are known to be deliv- 18 erable or undeliverable. 19 20 Addresses are verified by injecting probe messages into 21 the Postfix queue. Probe messages are run through all the 22 routing and rewriting machinery except for final delivery, 23 and are discarded rather than being deferred or bounced. 24 25 Address verification relies on the answer from the nearest 26 MTA for the specified address, and will therefore not 27 detect all undeliverable addresses. 28 29 The <a href="verify.8.html"><b>verify</b>(8)</a> server is designed to run under control by 30 the Postfix master server. It maintains an optional per- 31 sistent database. To avoid being interrupted by "postfix 32 stop" in the middle of a database update, the process runs 33 in a separate process group. 34 35 The <a href="verify.8.html"><b>verify</b>(8)</a> server implements the following requests: 36 37 <b>update</b> <i>address status text</i> 38 Update the status and text of the specified 39 address. 40 41 <b>query</b> <i>address</i> 42 Look up the <i>status</i> and <i>text</i> for the specified 43 <i>address</i>. If the status is unknown, a probe is sent 44 and an "in progress" status is returned. 45 46<b>SECURITY</b> 47 The address verification server is not security-sensitive. 48 It does not talk to the network, and it does not talk to 49 local users. The verify server can run chrooted at fixed 50 low privilege. 51 52 The address verification server can be coerced to store 53 unlimited amounts of garbage. Limiting the cache expiry 54 time trades one problem (disk space exhaustion) for 55 another one (poor response time to client requests). 56 57 With Postfix version 2.5 and later, the <a href="verify.8.html"><b>verify</b>(8)</a> server 58 no longer uses root privileges when opening the 59 <b><a href="postconf.5.html#address_verify_map">address_verify_map</a></b> cache file. The file should now be 60 stored under the Postfix-owned <b><a href="postconf.5.html#data_directory">data_directory</a></b>. As a 61 migration aid, an attempt to open a cache file under a 62 non-Postfix directory is redirected to the Postfix-owned 63 <b><a href="postconf.5.html#data_directory">data_directory</a></b>, and a warning is logged. 64 65<b>DIAGNOSTICS</b> 66 Problems and transactions are logged to <b>syslogd</b>(8). 67 68<b>BUGS</b> 69 Address verification probe messages add additional traffic 70 to the mail queue. Recipient verification may cause an 71 increased load on down-stream servers in the case of a 72 dictionary attack or a flood of backscatter bounces. 73 Sender address verification may cause your site to be 74 blacklisted by some providers. 75 76 If the persistent database ever gets corrupted then the 77 world comes to an end and human intervention is needed. 78 This violates a basic Postfix principle. 79 80<b>CONFIGURATION PARAMETERS</b> 81 Changes to <a href="postconf.5.html"><b>main.cf</b></a> are not picked up automatically, as 82 <a href="verify.8.html"><b>verify</b>(8)</a> processes are long-lived. Use the command "<b>post-</b> 83 <b>fix reload</b>" after a configuration change. 84 85 The text below provides only a parameter summary. See 86 <a href="postconf.5.html"><b>postconf</b>(5)</a> for more details including examples. 87 88<b>CACHE CONTROLS</b> 89 <b><a href="postconf.5.html#address_verify_map">address_verify_map</a> (see 'postconf -d' output)</b> 90 Lookup table for persistent address verification 91 status storage. 92 93 <b><a href="postconf.5.html#address_verify_sender">address_verify_sender</a> ($<a href="postconf.5.html#double_bounce_sender">double_bounce_sender</a>)</b> 94 The sender address to use in address verification 95 probes; prior to Postfix 2.5 the default was "post- 96 master". 97 98 <b><a href="postconf.5.html#address_verify_positive_expire_time">address_verify_positive_expire_time</a> (31d)</b> 99 The time after which a successful probe expires 100 from the address verification cache. 101 102 <b><a href="postconf.5.html#address_verify_positive_refresh_time">address_verify_positive_refresh_time</a> (7d)</b> 103 The time after which a successful address verifica- 104 tion probe needs to be refreshed. 105 106 <b><a href="postconf.5.html#address_verify_negative_cache">address_verify_negative_cache</a> (yes)</b> 107 Enable caching of failed address verification probe 108 results. 109 110 <b><a href="postconf.5.html#address_verify_negative_expire_time">address_verify_negative_expire_time</a> (3d)</b> 111 The time after which a failed probe expires from 112 the address verification cache. 113 114 <b><a href="postconf.5.html#address_verify_negative_refresh_time">address_verify_negative_refresh_time</a> (3h)</b> 115 The time after which a failed address verification 116 probe needs to be refreshed. 117 118 Available with Postfix 2.7 and later: 119 120 <b><a href="postconf.5.html#address_verify_cache_cleanup_interval">address_verify_cache_cleanup_interval</a> (12h)</b> 121 The amount of time between <a href="verify.8.html"><b>verify</b>(8)</a> address veri- 122 fication database cleanup runs. 123 124<b>PROBE MESSAGE ROUTING CONTROLS</b> 125 By default, probe messages are delivered via the same 126 route as regular messages. The following parameters can 127 be used to override specific message routing mechanisms. 128 129 <b><a href="postconf.5.html#address_verify_relayhost">address_verify_relayhost</a> ($<a href="postconf.5.html#relayhost">relayhost</a>)</b> 130 Overrides the <a href="postconf.5.html#relayhost">relayhost</a> parameter setting for 131 address verification probes. 132 133 <b><a href="postconf.5.html#address_verify_transport_maps">address_verify_transport_maps</a> ($<a href="postconf.5.html#transport_maps">transport_maps</a>)</b> 134 Overrides the <a href="postconf.5.html#transport_maps">transport_maps</a> parameter setting for 135 address verification probes. 136 137 <b><a href="postconf.5.html#address_verify_local_transport">address_verify_local_transport</a> ($<a href="postconf.5.html#local_transport">local_transport</a>)</b> 138 Overrides the <a href="postconf.5.html#local_transport">local_transport</a> parameter setting for 139 address verification probes. 140 141 <b><a href="postconf.5.html#address_verify_virtual_transport">address_verify_virtual_transport</a> ($<a href="postconf.5.html#virtual_transport">virtual_transport</a>)</b> 142 Overrides the <a href="postconf.5.html#virtual_transport">virtual_transport</a> parameter setting 143 for address verification probes. 144 145 <b><a href="postconf.5.html#address_verify_relay_transport">address_verify_relay_transport</a> ($<a href="postconf.5.html#relay_transport">relay_transport</a>)</b> 146 Overrides the <a href="postconf.5.html#relay_transport">relay_transport</a> parameter setting for 147 address verification probes. 148 149 <b><a href="postconf.5.html#address_verify_default_transport">address_verify_default_transport</a> ($<a href="postconf.5.html#default_transport">default_transport</a>)</b> 150 Overrides the <a href="postconf.5.html#default_transport">default_transport</a> parameter setting 151 for address verification probes. 152 153 Available in Postfix 2.3 and later: 154 155 <b><a href="postconf.5.html#address_verify_sender_dependent_relayhost_maps">address_verify_sender_dependent_relayhost_maps</a></b> 156 <b>($<a href="postconf.5.html#sender_dependent_relayhost_maps">sender_dependent_relayhost_maps</a>)</b> 157 Overrides the <a href="postconf.5.html#sender_dependent_relayhost_maps">sender_dependent_relayhost_maps</a> 158 parameter setting for address verification probes. 159 160 Available in Postfix 2.7 and later: 161 162 <b><a href="postconf.5.html#address_verify_sender_dependent_default_transport_maps">address_verify_sender_dependent_default_transport_maps</a></b> 163 <b>($<a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default_transport_maps</a>)</b> 164 Overrides the <a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default_trans</a>- 165 <a href="postconf.5.html#sender_dependent_default_transport_maps">port_maps</a> parameter setting for address verifica- 166 tion probes. 167 168<b>MISCELLANEOUS CONTROLS</b> 169 <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b> 170 The default location of the Postfix <a href="postconf.5.html">main.cf</a> and 171 <a href="master.5.html">master.cf</a> configuration files. 172 173 <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b> 174 How much time a Postfix daemon process may take to 175 handle a request before it is terminated by a 176 built-in watchdog timer. 177 178 <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b> 179 The time limit for sending or receiving information 180 over an internal communication channel. 181 182 <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b> 183 The process ID of a Postfix command or daemon 184 process. 185 186 <b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b> 187 The process name of a Postfix command or daemon 188 process. 189 190 <b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b> 191 The location of the Postfix top-level queue direc- 192 tory. 193 194 <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b> 195 The syslog facility of Postfix logging. 196 197 <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b> 198 The mail system name that is prepended to the 199 process name in syslog records, so that "smtpd" 200 becomes, for example, "postfix/smtpd". 201 202<b>SEE ALSO</b> 203 <a href="smtpd.8.html">smtpd(8)</a>, Postfix SMTP server 204 <a href="cleanup.8.html">cleanup(8)</a>, enqueue Postfix message 205 <a href="postconf.5.html">postconf(5)</a>, configuration parameters 206 syslogd(5), system logging 207 208<b>README FILES</b> 209 <a href="ADDRESS_VERIFICATION_README.html">ADDRESS_VERIFICATION_README</a>, address verification howto 210 211<b>LICENSE</b> 212 The Secure Mailer license must be distributed with this 213 software. 214 215<b>HISTORY</b> 216 This service was introduced with Postfix version 2.1. 217 218<b>AUTHOR(S)</b> 219 Wietse Venema 220 IBM T.J. Watson Research 221 P.O. Box 704 222 Yorktown Heights, NY 10598, USA 223 224 VERIFY(8) 225</pre> </body> </html> 226