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>PROBE MESSAGE CONTROLS</b> 89 <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> 90 The sender address to use in address verification 91 probes; prior to Postfix 2.5 the default was "post- 92 master". 93 94 Available with Postfix 2.9 and later: 95 96 <b><a href="postconf.5.html#address_verify_sender_ttl">address_verify_sender_ttl</a> (0s)</b> 97 The time between changes in the time-dependent por- 98 tion of address verification probe sender 99 addresses. 100 101<b>CACHE CONTROLS</b> 102 <b><a href="postconf.5.html#address_verify_map">address_verify_map</a> (see 'postconf -d' output)</b> 103 Lookup table for persistent address verification 104 status storage. 105 106 <b><a href="postconf.5.html#address_verify_positive_expire_time">address_verify_positive_expire_time</a> (31d)</b> 107 The time after which a successful probe expires 108 from the address verification cache. 109 110 <b><a href="postconf.5.html#address_verify_positive_refresh_time">address_verify_positive_refresh_time</a> (7d)</b> 111 The time after which a successful address verifica- 112 tion probe needs to be refreshed. 113 114 <b><a href="postconf.5.html#address_verify_negative_cache">address_verify_negative_cache</a> (yes)</b> 115 Enable caching of failed address verification probe 116 results. 117 118 <b><a href="postconf.5.html#address_verify_negative_expire_time">address_verify_negative_expire_time</a> (3d)</b> 119 The time after which a failed probe expires from 120 the address verification cache. 121 122 <b><a href="postconf.5.html#address_verify_negative_refresh_time">address_verify_negative_refresh_time</a> (3h)</b> 123 The time after which a failed address verification 124 probe needs to be refreshed. 125 126 Available with Postfix 2.7 and later: 127 128 <b><a href="postconf.5.html#address_verify_cache_cleanup_interval">address_verify_cache_cleanup_interval</a> (12h)</b> 129 The amount of time between <a href="verify.8.html"><b>verify</b>(8)</a> address veri- 130 fication database cleanup runs. 131 132<b>PROBE MESSAGE ROUTING CONTROLS</b> 133 By default, probe messages are delivered via the same 134 route as regular messages. The following parameters can 135 be used to override specific message routing mechanisms. 136 137 <b><a href="postconf.5.html#address_verify_relayhost">address_verify_relayhost</a> ($<a href="postconf.5.html#relayhost">relayhost</a>)</b> 138 Overrides the <a href="postconf.5.html#relayhost">relayhost</a> parameter setting for 139 address verification probes. 140 141 <b><a href="postconf.5.html#address_verify_transport_maps">address_verify_transport_maps</a> ($<a href="postconf.5.html#transport_maps">transport_maps</a>)</b> 142 Overrides the <a href="postconf.5.html#transport_maps">transport_maps</a> parameter setting for 143 address verification probes. 144 145 <b><a href="postconf.5.html#address_verify_local_transport">address_verify_local_transport</a> ($<a href="postconf.5.html#local_transport">local_transport</a>)</b> 146 Overrides the <a href="postconf.5.html#local_transport">local_transport</a> parameter setting for 147 address verification probes. 148 149 <b><a href="postconf.5.html#address_verify_virtual_transport">address_verify_virtual_transport</a> ($<a href="postconf.5.html#virtual_transport">virtual_transport</a>)</b> 150 Overrides the <a href="postconf.5.html#virtual_transport">virtual_transport</a> parameter setting 151 for address verification probes. 152 153 <b><a href="postconf.5.html#address_verify_relay_transport">address_verify_relay_transport</a> ($<a href="postconf.5.html#relay_transport">relay_transport</a>)</b> 154 Overrides the <a href="postconf.5.html#relay_transport">relay_transport</a> parameter setting for 155 address verification probes. 156 157 <b><a href="postconf.5.html#address_verify_default_transport">address_verify_default_transport</a> ($<a href="postconf.5.html#default_transport">default_transport</a>)</b> 158 Overrides the <a href="postconf.5.html#default_transport">default_transport</a> parameter setting 159 for address verification probes. 160 161 Available in Postfix 2.3 and later: 162 163 <b><a href="postconf.5.html#address_verify_sender_dependent_relayhost_maps">address_verify_sender_dependent_relayhost_maps</a></b> 164 <b>($<a href="postconf.5.html#sender_dependent_relayhost_maps">sender_dependent_relayhost_maps</a>)</b> 165 Overrides the <a href="postconf.5.html#sender_dependent_relayhost_maps">sender_dependent_relayhost_maps</a> 166 parameter setting for address verification probes. 167 168 Available in Postfix 2.7 and later: 169 170 <b><a href="postconf.5.html#address_verify_sender_dependent_default_transport_maps">address_verify_sender_dependent_default_transport_maps</a></b> 171 <b>($<a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default_transport_maps</a>)</b> 172 Overrides the <a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default_trans</a>- 173 <a href="postconf.5.html#sender_dependent_default_transport_maps">port_maps</a> parameter setting for address verifica- 174 tion probes. 175 176<b>MISCELLANEOUS CONTROLS</b> 177 <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b> 178 The default location of the Postfix <a href="postconf.5.html">main.cf</a> and 179 <a href="master.5.html">master.cf</a> configuration files. 180 181 <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b> 182 How much time a Postfix daemon process may take to 183 handle a request before it is terminated by a 184 built-in watchdog timer. 185 186 <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b> 187 The time limit for sending or receiving information 188 over an internal communication channel. 189 190 <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b> 191 The process ID of a Postfix command or daemon 192 process. 193 194 <b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b> 195 The process name of a Postfix command or daemon 196 process. 197 198 <b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b> 199 The location of the Postfix top-level queue direc- 200 tory. 201 202 <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b> 203 The syslog facility of Postfix logging. 204 205 <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b> 206 The mail system name that is prepended to the 207 process name in syslog records, so that "smtpd" 208 becomes, for example, "postfix/smtpd". 209 210<b>SEE ALSO</b> 211 <a href="smtpd.8.html">smtpd(8)</a>, Postfix SMTP server 212 <a href="cleanup.8.html">cleanup(8)</a>, enqueue Postfix message 213 <a href="postconf.5.html">postconf(5)</a>, configuration parameters 214 syslogd(5), system logging 215 216<b>README FILES</b> 217 <a href="ADDRESS_VERIFICATION_README.html">ADDRESS_VERIFICATION_README</a>, address verification howto 218 219<b>LICENSE</b> 220 The Secure Mailer license must be distributed with this 221 software. 222 223<b>HISTORY</b> 224 This service was introduced with Postfix version 2.1. 225 226<b>AUTHOR(S)</b> 227 Wietse Venema 228 IBM T.J. Watson Research 229 P.O. Box 704 230 Yorktown Heights, NY 10598, USA 231 232 VERIFY(8) 233</pre> </body> </html> 234