Postfix manual - ldap_table(5)

    LDAP_TABLE(5)                                                    LDAP_TABLE(5)

    NAME
           ldap_table - Postfix LDAP client configuration

    SYNOPSIS
           postmap -q "string" ldap:/etc/postfix/filename

           postmap -q - ldap:/etc/postfix/filename <inputfile

    DESCRIPTION
           The  Postfix  mail system uses optional tables for address rewriting or
           mail routing. These tables are usually in lmdb:, cdb:, hash:,  or  dbm:
           format.

           Alternatively,  lookup  tables  can be specified as LDAP databases.  To
           find out what types of lookup tables your Postfix system  supports  use
           the "postconf -m" command.

           In  order  to use LDAP lookups, define an LDAP source as a lookup table
           in main.cf, for example:

               alias_maps = ldap:/etc/postfix/ldap-aliases.cf

           The file /etc/postfix/ldap-aliases.cf has the same format as the  Post-
           fix  main.cf  file,  and can specify the parameters described below. An
           example is given at the end of this manual.

           This configuration method is available with  Postfix  version  2.1  and
           later.   See  the section "OBSOLETE MAIN.CF PARAMETERS" below for older
           Postfix versions.

           For details about LDAP SSL and STARTTLS, see the  section  on  SSL  and
           STARTTLS below.

    LIST MEMBERSHIP
           When  using  LDAP  to  store lists such as $mynetworks, $mydestination,
           $relay_domains, $local_recipient_maps, etc., it is important to  under-
           stand that the table must store each list member as a separate key. The
           table lookup verifies the *existence* of the key.  See  "Postfix  lists
           versus tables" in the DATABASE_README document for a discussion.

           Do  NOT create tables that return the full list of domains in $mydesti-
           nation or $relay_domains etc., or IP addresses in $mynetworks.

           DO create tables with each matching item as a key and with an arbitrary
           value. With LDAP databases it is not uncommon to return the key itself.

           For example, NEVER do this in a map defining $mydestination:

               query_filter = domain=*
               result_attribute = domain

           Do this instead:

               query_filter = domain=%s
               result_attribute = domain

    GENERAL LDAP PARAMETERS
           In the text below, default values  are  given  in  parentheses.   Note:
           don't  use  quotes  in these variables; at least, not until the Postfix
           configuration routines understand how to deal with quoted strings.

           server_host (default: localhost)
                  The name of the host running the LDAP server, e.g.

                      server_host = ldap.example.com

                  Depending on the LDAP client library you're using, it should  be
                  possible to specify multiple servers here, with the library try-
                  ing them in order should the first one fail. It should  also  be
                  possible to give each server in the list a different port (over-
                  riding server_port below), by naming them like

                      server_host = ldap.example.com:1444

                  NOTE: this client will  reconnect  immediately  after  a  single
                  failure,  and  will fail a lookup request after a second attempt
                  also fails.

                  With OpenLDAP, a (list of) LDAP URLs can be used to specify both
                  the hostname(s) and the port(s):

                      server_host = ldap://ldap.example.com:1444
                                  ldap://ldap2.example.com:1444

                  All  LDAP  URLs  accepted by the OpenLDAP library are supported,
                  including connections over UNIX domain  sockets,  and  LDAP  SSL
                  (the  last  one provided that OpenLDAP was compiled with support
                  for SSL):

                      server_host = ldapi://%2Fsome%2Fpath
                                  ldaps://ldap.example.com:636

           server_port (default: 389)
                  The port the LDAP server listens on, e.g.

                      server_port = 778

           timeout (default: 10 seconds)
                  The number of seconds a search can take before timing out,  e.g.

                      timeout = 5

           search_base (No default; you must configure this)
                  The RFC2253 base DN at which to conduct the search, e.g.

                      search_base = dc=your, dc=com

                  With Postfix 2.2 and later this parameter supports the following
                  '%' expansions:

                  %%     This is replaced by a literal '%' character.

                  %s     This is replaced by the input key.  RFC 2253  quoting  is
                         used  to  make sure that the input key does not add unex-
                         pected metacharacters.

                  %u     When the input key is an address of the form user@domain,
                         %u is replaced by the (RFC 2253) quoted local part of the
                         address.  Otherwise, %u is replaced by the entire  search
                         string.   If  the  localpart is empty, the search is sup-
                         pressed and returns no results.

                  %d     When the input key is an address of the form user@domain,
                         %d  is  replaced  by the (RFC 2253) quoted domain part of
                         the address.  Otherwise, the  search  is  suppressed  and
                         returns no results.

                  %[SUD] For the search_base parameter, the upper-case equivalents
                         of the  above  expansions  behave  identically  to  their
                         lower-case  counter-parts. With the result_format parame-
                         ter (previously called result_filter see the OTHER  OBSO-
                         LETE FEATURES section and below), they expand to the cor-
                         responding components of input key rather than the result
                         value.

                  %[1-9] The  patterns  %1,  %2, ... %9 are replaced by the corre-
                         sponding most significant component of  the  input  key's
                         domain.  If  the input key is user@mail.example.com, then
                         %1 is com, %2 is example and %3 is mail. If the input key
                         is  unqualified or does not have enough domain components
                         to satisfy all the specified patterns, the search is sup-
                         pressed and returns no results.

           query_filter (default: mailacceptinggeneralid=%s)
                  The  RFC2254  filter used to search the directory, where %s is a
                  substitute for the address Postfix is trying to resolve, e.g.

                      query_filter = (&(mail=%s)(paid_up=true))

                  This parameter supports the following '%' expansions:

                  %%     This is replaced by a literal '%' character. (Postfix 2.2
                         and later).

                  %s     This  is  replaced by the input key.  RFC 2254 quoting is
                         used to make sure that the input key does not  add  unex-
                         pected metacharacters.

                  %u     When the input key is an address of the form user@domain,
                         %u is replaced by the (RFC 2254) quoted local part of the
                         address.   Otherwise, %u is replaced by the entire search
                         string.  If the localpart is empty, the  search  is  sup-
                         pressed and returns no results.

                  %d     When the input key is an address of the form user@domain,
                         %d is replaced by the (RFC 2254) quoted  domain  part  of
                         the  address.   Otherwise,  the  search is suppressed and
                         returns no results.

                  %[SUD] The upper-case equivalents of the above expansions behave
                         in   the  query_filter  parameter  identically  to  their
                         lower-case counter-parts. With the result_format  parame-
                         ter  (previously called result_filter see the OTHER OBSO-
                         LETE FEATURES section and below), they expand to the cor-
                         responding components of input key rather than the result
                         value.

                         The above %S, %U and %D  expansions  are  available  with
                         Postfix 2.2 and later.

                  %[1-9] The  patterns  %1,  %2, ... %9 are replaced by the corre-
                         sponding most significant component of  the  input  key's
                         domain.  If  the input key is user@mail.example.com, then
                         %1 is com, %2 is example and %3 is mail. If the input key
                         is  unqualified or does not have enough domain components
                         to satisfy all the specified patterns, the search is sup-
                         pressed and returns no results.

                         The above %1, ..., %9 expansions are available with Post-
                         fix 2.2 and later.

                  The "domain" parameter described below limits the input keys  to
                  addresses  in  matching  domains. When the "domain" parameter is
                  non-empty, LDAP queries for unqualified addresses  or  addresses
                  in non-matching domains are suppressed and return no results.

                  NOTE: DO NOT put quotes around the query_filter parameter.

           result_format (default: %s)
                  Called  result_filter  in Postfix releases prior to 2.2.  Format
                  template applied to result attributes.  Most  commonly  used  to
                  append  (or prepend) text to the result. This parameter supports
                  the following '%' expansions:

                  %%     This is replaced by a literal '%' character. (Postfix 2.2
                         and later).

                  %s     This  is  replaced  by the value of the result attribute.
                         When result is empty it is skipped.

                  %u     When the result attribute value is an address of the form
                         user@domain,  %u  is  replaced  by  the local part of the
                         address. When the result has an  empty  localpart  it  is
                         skipped.

                  %d     When  a  result attribute value is an address of the form
                         user@domain, %d is replaced by the  domain  part  of  the
                         attribute  value.  When  the  result is unqualified it is
                         skipped.

                  %[SUD1-9]
                         The upper-case and decimal digit  expansions  interpolate
                         the  parts of the input key rather than the result. Their
                         behavior is identical to that described  with  query_fil-
                         ter,  and  in  fact  because  the  input  key is known in
                         advance, lookups whose  key  does  not  contain  all  the
                         information  specified  in  the  result template are sup-
                         pressed and return no results.

                         The above %S, %U, %D  and  %1,  ...,  %9  expansions  are
                         available with Postfix 2.2 and later.

                  For example, using "result_format = smtp:[%s]" allows one to use
                  a mailHost attribute as the basis of a transport(5) table. After
                  applying  the result format, multiple values are concatenated as
                  comma separated  strings.  The  expansion_limit  and  size_limit
                  parameters  explained  below allow one to restrict the number of
                  values in the result, which is especially useful for  maps  that
                  should return a single value.

                  The  default value %s specifies that each attribute value should
                  be used as is.

                  This parameter was  called  result_filter  in  Postfix  releases
                  prior  to  2.2. If no "result_format" is specified, the value of
                  "result_filter" will be used instead  before  resorting  to  the
                  default  value.  This provides compatibility with old configura-
                  tion files.

                  NOTE: DO NOT put quotes around the result format!

           domain (default: no domain list)
                  This is a list of domain names, paths to files, or  "type:table"
                  databases. When specified, only fully qualified search keys with
                  a *non-empty* localpart and a matching domain are  eligible  for
                  lookup:  'user'  lookups,  bare  domain  lookups  and  "@domain"
                  lookups are not performed. This  can  significantly  reduce  the
                  query load on the LDAP server.

                      domain = postfix.org, hash:/etc/postfix/searchdomains

                  It  is  best  not  to use LDAP to store the domains eligible for
                  LDAP lookups.

                  NOTE: DO NOT define this parameter for local(8) aliases.

                  This feature is available in Postfix 1.0 and later.

           result_attribute (default: maildrop)
                  The attribute(s) Postfix will read from  any  directory  entries
                  returned by the lookup, to be resolved to an email address.

                      result_attribute = mailbox, maildrop

                  Don't   rely   on   the  default  value  ("maildrop").  Set  the
                  result_attribute explicitly  in  all  ldap  table  configuration
                  files. This is particularly relevant when no result_attribute is
                  applicable, e.g. cases  in  which  leaf_result_attribute  and/or
                  terminal_result_attribute are used instead. The default value is
                  harmless if "maildrop" is also listed  as  a  leaf  or  terminal
                  result attribute, but it is best to not leave this to chance.

           special_result_attribute (default: empty)
                  The  attribute(s)  of  directory entries that can contain DNs or
                  RFC 2255 LDAP URLs. If found, a recursive search is performed to
                  retrieve  the entry referenced by the DN, or the entries matched
                  by the URL query.

                      special_result_attribute = memberdn

                  DN recursion retrieves the same result_attributes  as  the  main
                  query, including the special attributes for further recursion.

                  URL processing retrieves only those attributes that are included
                  in both the URL definition and as result  attributes  (ordinary,
                  special,  leaf or terminal) in the Postfix table definition.  If
                  the URL lists any of  the  table's  special  result  attributes,
                  these  are  retrieved  and used recursively. A URL that does not
                  specify any attribute selection, is equivalent (RFC 2255)  to  a
                  URL  that  selects  all  attributes,  in which case the selected
                  attributes will be the full set  of  result  attributes  in  the
                  Postfix table.

                  If an LDAP URL attribute-descriptor or the corresponding Postfix
                  LDAP table  result  attribute  (but  not  both)  uses  RFC  2255
                  sub-type  options  ("attr;option"), the attribute requested from
                  the LDAP server will include the sub-type option. In  all  other
                  cases,  the  URL  attribute  and  the table attribute must match
                  exactly. Attributes with options in both the URL and the Postfix
                  table  are  requested  only when the options are identical. LDAP
                  attribute-descriptor options are very  rarely  used,  most  LDAP
                  users  will  not  need  to concern themselves with this level of
                  nuanced detail.

           terminal_result_attribute (default: empty)
                  When one or more terminal result attributes are found in an LDAP
                  entry, all other result attributes are ignored and only the ter-
                  minal result attributes are returned. This is useful  for  dele-
                  gating expansion of group members to a particular host, by using
                  an optional "maildrop" attribute on selected groups to route the
                  group  to a specific host, where the group is expanded, possibly
                  via mailing-list manager or other special processing.

                      result_attribute =
                      terminal_result_attribute = maildrop

                  When  using  terminal  and/or  leaf   result   attributes,   the
                  result_attribute  is  best  set to an empty value when it is not
                  used, or else explicitly set to the desired value, even if it is
                  the default value "maildrop".

                  This feature is available with Postfix 2.4 or later.

           leaf_result_attribute (default: empty)
                  When  one  or  more  special  result  attributes  are found in a
                  non-terminal (see above) LDAP entry, leaf result attributes  are
                  excluded  from  the expansion of that entry. This is useful when
                  expanding groups and the desired mail  address  attribute(s)  of
                  the  member  objects  obtained  via DN or URI recursion are also
                  present in the group object. To only return the attribute values
                  from  the  leaf  objects  and  not the containing group, add the
                  attribute  to  the  leaf_result_attribute  list,  and  not   the
                  result_attribute  list,  which  is  always  expanded.  Note, the
                  default value of "result_attribute" is not empty, you  may  want
                  to set it explicitly empty when using "leaf_result_attribute" to
                  expand the group to a list of member  DN  addresses.  If  groups
                  have both member DN references AND attributes that hold multiple
                  string valued rfc822 addresses, then the string attributes go in
                  "result_attribute".   The  attributes  that  represent the email
                  addresses of objects referenced via a DN (or  LDAP  URI)  go  in
                  "leaf_result_attribute".

                      result_attribute = memberaddr
                      special_result_attribute = memberdn
                      terminal_result_attribute = maildrop
                      leaf_result_attribute = mail

                  When   using   terminal   and/or  leaf  result  attributes,  the
                  result_attribute is best set to an empty value when  it  is  not
                  used, or else explicitly set to the desired value, even if it is
                  the default value "maildrop".

                  This feature is available with Postfix 2.4 or later.

           scope (default: sub)
                  The LDAP search scope: sub, base, or one.  These translate  into
                  LDAP_SCOPE_SUBTREE, LDAP_SCOPE_BASE, and LDAP_SCOPE_ONELEVEL.

           bind (default: yes)
                  Whether  or how to bind to the LDAP server. Newer LDAP implemen-
                  tations don't require clients to bind, which saves  time.  Exam-
                  ple:

                      # Don't bind
                      bind = no
                      # Use SIMPLE bind
                      bind = yes
                      # Use SASL bind
                      bind = sasl

                  Postfix  versions  prior  to  2.8 only support "bind = no" which
                  means don't bind, and "bind = yes" which means do a SIMPLE bind.
                  Postfix  2.8 and later also supports "bind = SASL" when compiled
                  with LDAP SASL support as described in LDAP_README, it also adds
                  the  synonyms  "bind = none" and "bind = simple" for "bind = no"
                  and "bind = yes" respectively. See the SASL  section  below  for
                  additional parameters available with "bind = sasl".

                  If  you  do need to bind, you might consider configuring Postfix
                  to connect to the local machine on a port that's an  SSL  tunnel
                  to  your  LDAP server. If your LDAP server doesn't natively sup-
                  port SSL, put a tunnel (wrapper, proxy,  whatever  you  want  to
                  call  it)  on  that system too. This should prevent the password
                  from traversing the network in the clear.

           bind_dn (default: empty)
                  If you do have to bind, do  it  with  this  distinguished  name.
                  Example:

                      bind_dn = uid=postfix, dc=your, dc=com
                  With  "bind  = sasl" (see above) the DN may be optional for some
                  SASL mechanisms, don't specify a DN if not needed.

           bind_pw (default: empty)
                  The password for the distinguished name above. If  you  have  to
                  use  this,  you probably want to make the map configuration file
                  readable only by the  Postfix  user.  When  using  the  obsolete
                  ldap:ldapsource  syntax,  with  map parameters in main.cf, it is
                  not possible to  securely  store  the  bind  password.  This  is
                  because  main.cf  needs  to  be  world  readable  to allow local
                  accounts to submit mail via the sendmail command. Example:

                      bind_pw = postfixpw
                  With "bind = sasl" (see above) the password may be optional  for
                  some SASL mechanisms, don't specify a password if not needed.

           cache (IGNORED with a warning)

           cache_expiry (IGNORED with a warning)

           cache_size (IGNORED with a warning)
                  The  above parameters are NO LONGER SUPPORTED by Postfix.  Cache
                  support has been dropped from OpenLDAP as of release 2.1.13.

           recursion_limit (default: 1000)
                  A limit on the nesting  depth  of  DN  and  URL  special  result
                  attribute evaluation. The limit must be a non-zero positive num-
                  ber.

           expansion_limit (default: 0)
                  A limit on the total number of result elements  returned  (as  a
                  comma separated list) by a lookup against the map.  A setting of
                  zero disables the limit. Lookups fail with a temporary error  if
                  the  limit  is  exceeded.   Setting  the limit to 1 ensures that
                  lookups do not return multiple values.

           size_limit (default: $expansion_limit)
                  A limit on the number of LDAP entries  returned  by  any  single
                  LDAP search performed as part of the lookup. A setting of 0 dis-
                  ables the limit.  Expansion of DN and  URL  references  involves
                  nested  LDAP  queries,  each of which is separately subjected to
                  this limit.

                  Note: even a single LDAP  entry  can  generate  multiple  lookup
                  results,  via  multiple  result  attributes  and/or multi-valued
                  result attributes. This limit caps the per search resource  uti-
                  lization  on  the LDAP server, not the final multiplicity of the
                  lookup  result.  It  is  analogous  to  the   "-z"   option   of
                  "ldapsearch".

           dereference (default: 0)
                  When to dereference LDAP aliases. (Note that this has nothing do
                  with Postfix aliases.) The permitted values are those legal  for
                  the OpenLDAP/UM LDAP implementations:

                  0      never

                  1      when searching

                  2      when locating the base object for the search

                  3      always

                  See  ldap.h  or  the ldap_open(3) or ldapsearch(1) man pages for
                  more information. And if you're using an LDAP package  that  has
                  other  possible  values, please bring it to the attention of the
                  postfix-users@postfix.org mailing list.

           chase_referrals (default: 0)
                  Sets (or clears) LDAP_OPT_REFERRALS  (requires  LDAP  version  3
                  support).

           version (default: 2)
                  Specifies the LDAP protocol version to use.

           debuglevel (default: 0)
                  What level to set for debugging in the OpenLDAP libraries.

    LDAP SASL PARAMETERS
           If  you're  using  the  OpenLDAP  libraries compiled with SASL support,
           Postfix 2.8 and later built with LDAP  SASL  support  as  described  in
           LDAP_README can authenticate to LDAP servers via SASL.

           This  enables  authentication  to  the LDAP server via mechanisms other
           than a simple password. The added flexibility has  a  cost:  it  is  no
           longer  practical to set an explicit timeout on the duration of an LDAP
           bind operation. Under adverse conditions, whether  a  SASL  bind  times
           out,  or  if  it does, the duration of the timeout is determined by the
           LDAP and SASL libraries.

           It is best to use tables that use SASL binds via proxymap(8), this  way
           the  requesting  process  can  time-out the proxymap request. This also
           lets you tailer the process environment by overriding  the  proxymap(8)
           import_environment  setting  in  master.cf(5). Special environment set-
           tings may be needed to configure GSSAPI credential caches or other SASL
           mechanism  specific  options.  The  GSSAPI  credentials  used  for LDAP
           lookups may need to be different than say those used  for  the  Postfix
           SMTP client to authenticate to remote servers.

           Using  SASL  mechanisms  requires  LDAP protocol version 3, the default
           protocol version is 2 for backwards compatibility. You must  set  "ver-
           sion = 3" in addition to "bind = sasl".

           The following parameters are relevant to using LDAP with SASL

           sasl_mechs (default: empty)
                  Space separated list of SASL mechanism(s) to try.

           sasl_realm (default: empty)
                  SASL Realm to use, if applicable.

           sasl_authz_id (default: empty)
                  The SASL authorization identity to assert, if applicable.

           sasl_minssf (default: 0)
                  The  minimum required sasl security factor required to establish
                  a connection.

    LDAP SSL AND STARTTLS PARAMETERS
           If you're using the OpenLDAP libraries compiled with SSL support, Post-
           fix can connect to LDAP SSL servers and can issue the STARTTLS command.

           LDAP SSL service can be requested by  using  a  LDAP  SSL  URL  in  the
           server_host parameter:

               server_host = ldaps://ldap.example.com:636

           STARTTLS can be turned on with the start_tls parameter:

               start_tls = yes

           Both forms require LDAP protocol version 3, which has to be set explic-
           itly with:

               version = 3

           If any of the Postfix programs querying the map is configured  in  mas-
           ter.cf  to run chrooted, all the certificates and keys involved have to
           be copied to the chroot jail. Of course, the private keys  should  only
           be readable by the user "postfix".

           The following parameters are relevant to LDAP SSL and STARTTLS:

           start_tls (default: no)
                  Whether  or not to issue STARTTLS upon connection to the server.
                  Don't set this with LDAP SSL (the SSL session is setup automati-
                  cally when the TCP connection is opened).

           tls_ca_cert_dir (No default; set either this or tls_ca_cert_file)
                  Directory  containing  X509 Certification Authority certificates
                  in PEM format which are  to  be  recognized  by  the  client  in
                  SSL/TLS  connections. The files each contain one CA certificate.
                  The files are looked up by the CA subject name hash value, which
                  must  hence  be  available. If more than one CA certificate with
                  the same name hash value exist, the extension must be  different
                  (e.g.  9d66eef0.0,  9d66eef0.1  etc). The search is performed in
                  the ordering of the extension number, regardless of other  prop-
                  erties  of  the certificates. Use the c_rehash utility (from the
                  OpenSSL distribution) to create the necessary links.

           tls_ca_cert_file (No default; set either this or tls_ca_cert_dir)
                  File containing the X509 Certification Authority certificates in
                  PEM  format  which are to be recognized by the client in SSL/TLS
                  connections. This setting takes precedence over tls_ca_cert_dir.

           tls_cert (No default; you must set this)
                  File  containing  client's  X509  certificate  to be used by the
                  client in SSL/ TLS connections.

           tls_key (No default; you must set this)
                  File containing the  private  key  corresponding  to  the  above
                  tls_cert.

           tls_require_cert (default: no)
                  Whether  or  not  to request server's X509 certificate and check
                  its validity when establishing SSL/TLS  connections.   The  sup-
                  ported values are no and yes.

                  With  no, the server certificate trust chain is not checked, but
                  with OpenLDAP prior to 2.1.13, the name in the  server  certifi-
                  cate  must still match the LDAP server name. With OpenLDAP 2.0.0
                  to 2.0.11 the server name is not necessarily what you specified,
                  rather  it is determined (by reverse lookup) from the IP address
                  of the LDAP server connection. With OpenLDAP  prior  to  2.0.13,
                  subjectAlternativeName extensions in the LDAP server certificate
                  are ignored: the server name must match the subject  CommonName.
                  The  no setting corresponds to the never value of TLS_REQCERT in
                  LDAP client configuration files.

                  Don't use TLS with OpenLDAP 2.0.x (and especially with x <=  11)
                  if you can avoid it.

                  With yes, the server certificate must be issued by a trusted CA,
                  and not be expired. The LDAP server name must match one  of  the
                  name(s) found in the certificate (see above for OpenLDAP library
                  version dependent behavior). The yes setting corresponds to  the
                  demand  value of TLS_REQCERT in LDAP client configuration files.

                  The "try" and "allow" values of TLS_REQCERT have no  equivalents
                  here.  They are not available with OpenLDAP 2.0, and in any case
                  have questionable security properties. Either you want TLS veri-
                  fied LDAP connections, or you don't.

                  The  yes  value only works correctly with Postfix 2.5 and later,
                  or with OpenLDAP 2.0. Earlier Postfix releases or later OpenLDAP
                  releases don't work together with this setting. Support for LDAP
                  over TLS was added to Postfix based on the OpenLDAP 2.0 API.

           tls_random_file (No default)
                  Path of a file to obtain random bits from when /dev/[u]random is
                  not  available, to be used by the client in SSL/TLS connections.

           tls_cipher_suite (No default)
                  Cipher suite to use in SSL/TLS negotiations.

    EXAMPLE
           Here's a basic example for using LDAP  to  look  up  local(8)  aliases.
           Assume that in main.cf, you have:

               alias_maps = hash:/etc/aliases,
                       ldap:/etc/postfix/ldap-aliases.cf

           and in ldap:/etc/postfix/ldap-aliases.cf you have:

               server_host = ldap.example.com
               search_base = dc=example, dc=com

           Upon  receiving mail for a local address "ldapuser" that isn't found in
           the /etc/aliases database, Postfix will search the LDAP server  listen-
           ing  at port 389 on ldap.example.com.  It will bind anonymously, search
           for any directory entries  whose  mailacceptinggeneralid  attribute  is
           "ldapuser",  read the "maildrop" attributes of those found, and build a
           list of their maildrops, which will be treated as RFC822  addresses  to
           which the message will be delivered.

    OBSOLETE MAIN.CF PARAMETERS
           For  backwards compatibility with Postfix version 2.0 and earlier, LDAP
           parameters can also be defined in main.cf.  Specify as  LDAP  source  a
           name  that  doesn't  begin  with a slash or a dot.  The LDAP parameters
           will then be accessible as the name you've given the source in its def-
           inition, an underscore, and the name of the parameter.  For example, if
           the map is specified as "ldap:ldapsource", the "server_host"  parameter
           below would be defined in main.cf as "ldapsource_server_host".

           Note: with this form, the passwords for the LDAP sources are written in
           main.cf, which is normally world-readable.  Support for this form  will
           be removed in a future Postfix version.

    OTHER OBSOLETE FEATURES
           result_filter (No default)
                  For  backwards  compatibility  with  the  pre  2.2 LDAP clients,
                  result_filter can for now be used instead of result_format, when
                  the  latter  parameter  is  not  also  set.  The new name better
                  reflects the  function  of  the  parameter.  This  compatibility
                  interface may be removed in a future release.

    SEE ALSO
           postmap(1), Postfix lookup table manager
           postconf(5), configuration parameters
           mysql_table(5), MySQL lookup tables
           pgsql_table(5), PostgreSQL lookup tables

    README FILES
           DATABASE_README, Postfix lookup table overview
           LDAP_README, Postfix LDAP client guide

    LICENSE
           The Secure Mailer license must be distributed with this software.

    AUTHOR(S)
           Carsten Hoeger, Hery Rakotoarisoa, John Hensley, Keith Stevenson,  LaM-
           ont  Jones,  Liviu Daia, Manuel Guesdon, Mike Mattice, Prabhat K Singh,
           Sami Haahtinen, Samuel Tardieu, Victor Duchovni, and many others.

                                                                     LDAP_TABLE(5)