PROXYMAP(8)                                           PROXYMAP(8)

       proxymap - Postfix lookup table proxy server

       proxymap [generic Postfix daemon options]

       The  proxymap  server provides read-only table lookup ser-
       vice to Postfix processes. The purpose of the service is:

       o      To overcome chroot  restrictions.  For  example,  a
              chrooted  SMTP  server  needs  access to the system
              passwd file in order to reject mail  for  non-exis-
              tent  local  addresses,  but it is not practical to
              maintain a copy of the passwd file  in  the  chroot
              jail.  The solution:

              local_recipient_maps =
                  proxy:unix:passwd.byname $alias_maps

       o      To  consolidate the number of open lookup tables by
              sharing one open table  among  multiple  processes.
              For  example,  making  mysql connections from every
              Postfix daemon process results in "too many connec-
              tions" errors. The solution:

              virtual_alias_maps =

              The  total  number of connections is limited by the
              number of proxymap server processes.

       The proxymap server implements the following requests:

       open maptype:mapname flags
              Open the table with type maptype and name  mapname,
              as controlled by flags. The reply includes the map-
              type dependent flags (to distinguish a fixed string
              table from a regular expression table).

       lookup maptype:mapname flags key
              Look  up  the  data stored under the requested key.
              The reply is the  request  completion  status  code
              (below)  and  the  lookup  result  value.  The map-
              type:mapname and flags are the  same  as  with  the
              open request.

       There  is  no  close  command,  nor  are tables implicitly
       closed when a client disconnects. The purpose is to  share
       tables among multiple client processes.

       proxymap  servers  run under control by the Postfix master
       server.  Each server can handle multiple simultaneous con-
       nections.   When  all servers are busy while a client con-
       nects, the master creates a new proxymap  server  process,
       provided  that  the  process  limit is not exceeded.  Each
       server terminates after serving at least $max_use  clients
       or after $max_idle seconds of idle time.

       The  proxymap  server  opens only tables that are approved
       via the proxy_read_maps configuration parameter, does  not
       talk  to  users,  and  can  run  at  fixed  low privilege,
       chrooted or not.  However,  running  the  proxymap  server
       chrooted  severely  limits  usability, because it can open
       only chrooted tables.

       The proxymap server is not a trusted daemon  process,  and
       must  not be used to look up sensitive information such as
       user or group IDs, mailbox file/directory names or  exter-
       nal commands.

       Problems and transactions are logged to syslogd(8).

       The  proxymap server provides service to multiple clients,
       and must therefore not be used for tables that have  high-
       latency lookups.

       On  busy  mail  systems  a long time may pass before prox-
       ymap(8) relevant changes to are picked up. Use the
       command "postfix reload" to speed up a change.

       The  text  below  provides  only  a parameter summary. See
       postconf(5) for more details including examples.

       config_directory (see 'postconf -d' output)
              The default location of  the  Postfix  and
     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.

       max_idle (100s)
              The maximum amount of time  that  an  idle  Postfix
              daemon  process  waits for the next service request
              before exiting.

       max_use (100)
              The maximal number of connection requests before  a
              Postfix daemon process terminates.

       process_id (read-only)
              The  process ID of a Postfix command or daemon pro-

       process_name (read-only)
              The process name of a  Postfix  command  or  daemon

       proxy_read_maps (see 'postconf -d' output)
              The  lookup  tables  that the proxymap(8) server is
              allowed to access.

       The Secure Mailer license must be  distributed  with  this

       The proxymap service was introduced with Postfix 2.0.

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA