postfix-master/verify.8.html

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   7 VERIFY(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>