# cat main.cf
     1  # Global Postfix configuration file. This file lists only a subset
     2  # of all parameters. For the syntax, and for a complete parameter
     3  # list, see the postconf(5) manual page (command: "man 5 postconf").
     4  #
     5  # For common configuration examples, see BASIC_CONFIGURATION_README
     6  # and STANDARD_CONFIGURATION_README. To find these documents, use
     7  # the command "postconf html_directory readme_directory", or go to
     8  # http://www.postfix.org/.
     9  #
    10  # For best results, change no more than 2-3 parameters at a time,
    11  # and test if Postfix still works after every change.
    12
    13  # SOFT BOUNCE
    14  #
    15  # The soft_bounce parameter provides a limited safety net for
    16  # testing.  When soft_bounce is enabled, mail will remain queued that
    17  # would otherwise bounce. This parameter disables locally-generated
    18  # bounces, and prevents the SMTP server from rejecting mail permanently
    19  # (by changing 5xx replies into 4xx replies). However, soft_bounce
    20  # is no cure for address rewriting mistakes or mail routing mistakes.
    21  #
    22  #soft_bounce = no
    23
    24  # LOCAL PATHNAME INFORMATION
    25  #
    26  # The queue_directory specifies the location of the Postfix queue.
    27  # This is also the root directory of Postfix daemons that run chrooted.
    28  # See the files in examples/chroot-setup for setting up Postfix chroot
    29  # environments on different UNIX systems.
    30  #
    31  queue_directory = /var/spool/postfix
    32
    33  # The command_directory parameter specifies the location of all
    34  # postXXX commands.
    35  #
    36  command_directory = /usr/sbin
    37
    38  # The daemon_directory parameter specifies the location of all Postfix
    39  # daemon programs (i.e. programs listed in the master.cf file). This
    40  # directory must be owned by root.
    41  #
    42  daemon_directory = /usr/libexec/postfix
    43
    44  # The data_directory parameter specifies the location of Postfix-writable
    45  # data files (caches, random numbers). This directory must be owned
    46  # by the mail_owner account (see below).
    47  #
    48  data_directory = /var/lib/postfix
    49
    50  # QUEUE AND PROCESS OWNERSHIP
    51  #
    52  # The mail_owner parameter specifies the owner of the Postfix queue
    53  # and of most Postfix daemon processes.  Specify the name of a user
    54  # account THAT DOES NOT SHARE ITS USER OR GROUP ID WITH OTHER ACCOUNTS
    55  # AND THAT OWNS NO OTHER FILES OR PROCESSES ON THE SYSTEM.  In
    56  # particular, don‘t specify nobody or daemon. PLEASE USE A DEDICATED
    57  # USER.
    58  #
    59  mail_owner = postfix
    60
    61  # The default_privs parameter specifies the default rights used by
    62  # the local delivery agent for delivery to external file or command.
    63  # These rights are used in the absence of a recipient user context.
    64  # DO NOT SPECIFY A PRIVILEGED USER OR THE POSTFIX OWNER.
    65  #
    66  #default_privs = nobody
    67
    68  # INTERNET HOST AND DOMAIN NAMES
    69  #
    70  # The myhostname parameter specifies the internet hostname of this
    71  # mail system. The default is to use the fully-qualified domain name
    72  # from gethostname(). $myhostname is used as a default value for many
    73  # other configuration parameters.
    74  #
    75  #myhostname = host.domain.tld
    76  #myhostname = virtual.domain.tld
    77
    78  # The mydomain parameter specifies the local internet domain name.
    79  # The default is to use $myhostname minus the first component.
    80  # $mydomain is used as a default value for many other configuration
    81  # parameters.
    82  #
    83  #mydomain = domain.tld
    84
    85  # SENDING MAIL
    86  #
    87  # The myorigin parameter specifies the domain that locally-posted
    88  # mail appears to come from. The default is to append $myhostname,
    89  # which is fine for small sites.  If you run a domain with multiple
    90  # machines, you should (1) change this to $mydomain and (2) set up
    91  # a domain-wide alias database that aliases each user to
    92  # user@that.users.mailhost.
    93  #
    94  # For the sake of consistency between sender and recipient addresses,
    95  # myorigin also specifies the default domain name that is appended
    96  # to recipient addresses that have no @domain part.
    97  #
    98  #myorigin = $myhostname
    99  #myorigin = $mydomain
   100
   101  # RECEIVING MAIL
   102
   103  # The inet_interfaces parameter specifies the network interface
   104  # addresses that this mail system receives mail on.  By default,
   105  # the software claims all active interfaces on the machine. The
   106  # parameter also controls delivery of mail to user@[ip.address].
   107  #
   108  # See also the proxy_interfaces parameter, for network addresses that
   109  # are forwarded to us via a proxy or network address translator.
   110  #
   111  # Note: you need to stop/start Postfix when this parameter changes.
   112  #
   113  #inet_interfaces = all
   114  #inet_interfaces = $myhostname
   115  #inet_interfaces = $myhostname, localhost
   116  inet_interfaces = localhost
   117
   118  # Enable IPv4, and IPv6 if supported
   119  inet_protocols = all
   120
   121  # The proxy_interfaces parameter specifies the network interface
   122  # addresses that this mail system receives mail on by way of a
   123  # proxy or network address translation unit. This setting extends
   124  # the address list specified with the inet_interfaces parameter.
   125  #
   126  # You must specify your proxy/NAT addresses when your system is a
   127  # backup MX host for other domains, otherwise mail delivery loops
   128  # will happen when the primary MX host is down.
   129  #
   130  #proxy_interfaces =
   131  #proxy_interfaces = 1.2.3.4
   132
   133  # The mydestination parameter specifies the list of domains that this
   134  # machine considers itself the final destination for.
   135  #
   136  # These domains are routed to the delivery agent specified with the
   137  # local_transport parameter setting. By default, that is the UNIX
   138  # compatible delivery agent that lookups all recipients in /etc/passwd
   139  # and /etc/aliases or their equivalent.
   140  #
   141  # The default is $myhostname + localhost.$mydomain.  On a mail domain
   142  # gateway, you should also include $mydomain.
   143  #
   144  # Do not specify the names of virtual domains - those domains are
   145  # specified elsewhere (see VIRTUAL_README).
   146  #
   147  # Do not specify the names of domains that this machine is backup MX
   148  # host for. Specify those names via the relay_domains settings for
   149  # the SMTP server, or use permit_mx_backup if you are lazy (see
   150  # STANDARD_CONFIGURATION_README).
   151  #
   152  # The local machine is always the final destination for mail addressed
   153  # to user@[the.net.work.address] of an interface that the mail system
   154  # receives mail on (see the inet_interfaces parameter).
   155  #
   156  # Specify a list of host or domain names, /file/name or type:table
   157  # patterns, separated by commas and/or whitespace. A /file/name
   158  # pattern is replaced by its contents; a type:table is matched when
   159  # a name matches a lookup key (the right-hand side is ignored).
   160  # Continue long lines by starting the next line with whitespace.
   161  #
   162  # See also below, section "REJECTING MAIL FOR UNKNOWN LOCAL USERS".
   163  #
   164  mydestination = $myhostname, localhost.$mydomain, localhost
   165  #mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
   166  #mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain,
   167  #       mail.$mydomain, www.$mydomain, ftp.$mydomain
   168
   169  # REJECTING MAIL FOR UNKNOWN LOCAL USERS
   170  #
   171  # The local_recipient_maps parameter specifies optional lookup tables
   172  # with all names or addresses of users that are local with respect
   173  # to $mydestination, $inet_interfaces or $proxy_interfaces.
   174  #
   175  # If this parameter is defined, then the SMTP server will reject
   176  # mail for unknown local users. This parameter is defined by default.
   177  #
   178  # To turn off local recipient checking in the SMTP server, specify
   179  # local_recipient_maps = (i.e. empty).
   180  #
   181  # The default setting assumes that you use the default Postfix local
   182  # delivery agent for local delivery. You need to update the
   183  # local_recipient_maps setting if:
   184  #
   185  # - You define $mydestination domain recipients in files other than
   186  #   /etc/passwd, /etc/aliases, or the $virtual_alias_maps files.
   187  #   For example, you define $mydestination domain recipients in    
   188  #   the $virtual_mailbox_maps files.
   189  #
   190  # - You redefine the local delivery agent in master.cf.
   191  #
   192  # - You redefine the "local_transport" setting in main.cf.
   193  #
   194  # - You use the "luser_relay", "mailbox_transport", or "fallback_transport"
   195  #   feature of the Postfix local delivery agent (see local(8)).
   196  #
   197  # Details are described in the LOCAL_RECIPIENT_README file.
   198  #
   199  # Beware: if the Postfix SMTP server runs chrooted, you probably have
   200  # to access the passwd file via the proxymap service, in order to
   201  # overcome chroot restrictions. The alternative, having a copy of
   202  # the system passwd file in the chroot jail is just not practical.
   203  #
   204  # The right-hand side of the lookup tables is conveniently ignored.
   205  # In the left-hand side, specify a bare username, an @domain.tld
   206  # wild-card, or specify a user@domain.tld address.
   207  #
   208  #local_recipient_maps = unix:passwd.byname $alias_maps
   209  #local_recipient_maps = proxy:unix:passwd.byname $alias_maps
   210  #local_recipient_maps =
   211
   212  # The unknown_local_recipient_reject_code specifies the SMTP server
   213  # response code when a recipient domain matches $mydestination or
   214  # ${proxy,inet}_interfaces, while $local_recipient_maps is non-empty
   215  # and the recipient address or address local-part is not found.
   216  #
   217  # The default setting is 550 (reject mail) but it is safer to start
   218  # with 450 (try again later) until you are certain that your
   219  # local_recipient_maps settings are OK.
   220  #
   221  unknown_local_recipient_reject_code = 550
   222
   223  # TRUST AND RELAY CONTROL
   224
   225  # The mynetworks parameter specifies the list of "trusted" SMTP
   226  # clients that have more privileges than "strangers".
   227  #
   228  # In particular, "trusted" SMTP clients are allowed to relay mail
   229  # through Postfix.  See the smtpd_recipient_restrictions parameter
   230  # in postconf(5).
   231  #
   232  # You can specify the list of "trusted" network addresses by hand
   233  # or you can let Postfix do it for you (which is the default).
   234  #
   235  # By default (mynetworks_style = subnet), Postfix "trusts" SMTP
   236  # clients in the same IP subnetworks as the local machine.
   237  # On Linux, this does works correctly only with interfaces specified
   238  # with the "ifconfig" command.
   239  #
   240  # Specify "mynetworks_style = class" when Postfix should "trust" SMTP
   241  # clients in the same IP class A/B/C networks as the local machine.
   242  # Don‘t do this with a dialup site - it would cause Postfix to "trust"
   243  # your entire provider‘s network.  Instead, specify an explicit
   244  # mynetworks list by hand, as described below.
   245  #  
   246  # Specify "mynetworks_style = host" when Postfix should "trust"
   247  # only the local machine.
   248  #
   249  #mynetworks_style = class
   250  #mynetworks_style = subnet
   251  #mynetworks_style = host
   252
   253  # Alternatively, you can specify the mynetworks list by hand, in
   254  # which case Postfix ignores the mynetworks_style setting.
   255  #
   256  # Specify an explicit list of network/netmask patterns, where the
   257  # mask specifies the number of bits in the network part of a host
   258  # address.
   259  #
   260  # You can also specify the absolute pathname of a pattern file instead
   261  # of listing the patterns here. Specify type:table for table-based lookups
   262  # (the value on the table right-hand side is not used).
   263  #
   264  #mynetworks = 168.100.189.0/28, 127.0.0.0/8
   265  #mynetworks = $config_directory/mynetworks
   266  #mynetworks = hash:/etc/postfix/network_table
   267
   268  # The relay_domains parameter restricts what destinations this system will
   269  # relay mail to.  See the smtpd_recipient_restrictions description in
   270  # postconf(5) for detailed information.
   271  #
   272  # By default, Postfix relays mail
   273  # - from "trusted" clients (IP address matches $mynetworks) to any destination,
   274  # - from "untrusted" clients to destinations that match $relay_domains or
   275  #   subdomains thereof, except addresses with sender-specified routing.
   276  # The default relay_domains value is $mydestination.
   277  #
   278  # In addition to the above, the Postfix SMTP server by default accepts mail
   279  # that Postfix is final destination for:
   280  # - destinations that match $inet_interfaces or $proxy_interfaces,
   281  # - destinations that match $mydestination
   282  # - destinations that match $virtual_alias_domains,
   283  # - destinations that match $virtual_mailbox_domains.
   284  # These destinations do not need to be listed in $relay_domains.
   285  #
   286  # Specify a list of hosts or domains, /file/name patterns or type:name
   287  # lookup tables, separated by commas and/or whitespace.  Continue
   288  # long lines by starting the next line with whitespace. A file name
   289  # is replaced by its contents; a type:name table is matched when a
   290  # (parent) domain appears as lookup key.
   291  #
   292  # NOTE: Postfix will not automatically forward mail for domains that
   293  # list this system as their primary or backup MX host. See the
   294  # permit_mx_backup restriction description in postconf(5).
   295  #
   296  #relay_domains = $mydestination
   297
   298  # INTERNET OR INTRANET
   299
   300  # The relayhost parameter specifies the default host to send mail to
   301  # when no entry is matched in the optional transport(5) table. When
   302  # no relayhost is given, mail is routed directly to the destination.
   303  #
   304  # On an intranet, specify the organizational domain name. If your
   305  # internal DNS uses no MX records, specify the name of the intranet
   306  # gateway host instead.
   307  #
   308  # In the case of SMTP, specify a domain, host, host:port, [host]:port,
   309  # [address] or [address]:port; the form [host] turns off MX lookups.
   310  #
   311  # If you‘re connected via UUCP, see also the default_transport parameter.
   312  #
   313  #relayhost = $mydomain
   314  #relayhost = [gateway.my.domain]
   315  #relayhost = [mailserver.isp.tld]
   316  #relayhost = uucphost
   317  #relayhost = [an.ip.add.ress]
   318
   319  # REJECTING UNKNOWN RELAY USERS
   320  #
   321  # The relay_recipient_maps parameter specifies optional lookup tables
   322  # with all addresses in the domains that match $relay_domains.
   323  #
   324  # If this parameter is defined, then the SMTP server will reject
   325  # mail for unknown relay users. This feature is off by default.
   326  #
   327  # The right-hand side of the lookup tables is conveniently ignored.
   328  # In the left-hand side, specify an @domain.tld wild-card, or specify
   329  # a user@domain.tld address.
   330  #
   331  #relay_recipient_maps = hash:/etc/postfix/relay_recipients
   332
   333  # INPUT RATE CONTROL
   334  #
   335  # The in_flow_delay configuration parameter implements mail input
   336  # flow control. This feature is turned on by default, although it
   337  # still needs further development (it‘s disabled on SCO UNIX due
   338  # to an SCO bug).
   339  #
   340  # A Postfix process will pause for $in_flow_delay seconds before
   341  # accepting a new message, when the message arrival rate exceeds the
   342  # message delivery rate. With the default 100 SMTP server process
   343  # limit, this limits the mail inflow to 100 messages a second more
   344  # than the number of messages delivered per second.
   345  #
   346  # Specify 0 to disable the feature. Valid delays are 0..10.
   347  #
   348  #in_flow_delay = 1s
   349
   350  # ADDRESS REWRITING
   351  #
   352  # The ADDRESS_REWRITING_README document gives information about
   353  # address masquerading or other forms of address rewriting including
   354  # username->Firstname.Lastname mapping.
   355
   356  # ADDRESS REDIRECTION (VIRTUAL DOMAIN)
   357  #
   358  # The VIRTUAL_README document gives information about the many forms
   359  # of domain hosting that Postfix supports.
   360
   361  # "USER HAS MOVED" BOUNCE MESSAGES
   362  #
   363  # See the discussion in the ADDRESS_REWRITING_README document.
   364
   365  # TRANSPORT MAP
   366  #
   367  # See the discussion in the ADDRESS_REWRITING_README document.
   368
   369  # ALIAS DATABASE
   370  #
   371  # The alias_maps parameter specifies the list of alias databases used
   372  # by the local delivery agent. The default list is system dependent.
   373  #
   374  # On systems with NIS, the default is to search the local alias
   375  # database, then the NIS alias database. See aliases(5) for syntax
   376  # details.
   377  #
   378  # If you change the alias database, run "postalias /etc/aliases" (or
   379  # wherever your system stores the mail alias file), or simply run
   380  # "newaliases" to build the necessary DBM or DB file.
   381  #
   382  # It will take a minute or so before changes become visible.  Use
   383  # "postfix reload" to eliminate the delay.
   384  #
   385  #alias_maps = dbm:/etc/aliases
   386  alias_maps = hash:/etc/aliases
   387  #alias_maps = hash:/etc/aliases, nis:mail.aliases
   388  #alias_maps = netinfo:/aliases
   389
   390  # The alias_database parameter specifies the alias database(s) that
   391  # are built with "newaliases" or "sendmail -bi".  This is a separate
   392  # configuration parameter, because alias_maps (see above) may specify
   393  # tables that are not necessarily all under control by Postfix.
   394  #
   395  #alias_database = dbm:/etc/aliases
   396  #alias_database = dbm:/etc/mail/aliases
   397  alias_database = hash:/etc/aliases
   398  #alias_database = hash:/etc/aliases, hash:/opt/majordomo/aliases
   399
   400  # ADDRESS EXTENSIONS (e.g., user+foo)
   401  #
   402  # The recipient_delimiter parameter specifies the separator between
   403  # user names and address extensions (user+foo). See canonical(5),
   404  # local(8), relocated(5) and virtual(5) for the effects this has on
   405  # aliases, canonical, virtual, relocated and .forward file lookups.
   406  # Basically, the software tries user+foo and .forward+foo before
   407  # trying user and .forward.
   408  #
   409  #recipient_delimiter = +
   410
   411  # DELIVERY TO MAILBOX
   412  #
   413  # The home_mailbox parameter specifies the optional pathname of a
   414  # mailbox file relative to a user‘s home directory. The default
   415  # mailbox file is /var/spool/mail/user or /var/mail/user.  Specify
   416  # "Maildir/" for qmail-style delivery (the / is required).
   417  #
   418  #home_mailbox = Mailbox
   419  #home_mailbox = Maildir/
   420   
   421  # The mail_spool_directory parameter specifies the directory where
   422  # UNIX-style mailboxes are kept. The default setting depends on the
   423  # system type.
   424  #
   425  #mail_spool_directory = /var/mail
   426  #mail_spool_directory = /var/spool/mail
   427
   428  # The mailbox_command parameter specifies the optional external
   429  # command to use instead of mailbox delivery. The command is run as
   430  # the recipient with proper HOME, SHELL and LOGNAME environment settings.
   431  # Exception:  delivery for root is done as $default_user.
   432  #
   433  # Other environment variables of interest: USER (recipient username),
   434  # EXTENSION (address extension), DOMAIN (domain part of address),
   435  # and LOCAL (the address localpart).
   436  #
   437  # Unlike other Postfix configuration parameters, the mailbox_command
   438  # parameter is not subjected to $parameter substitutions. This is to
   439  # make it easier to specify shell syntax (see example below).
   440  #
   441  # Avoid shell meta characters because they will force Postfix to run
   442  # an expensive shell process. Procmail alone is expensive enough.
   443  #
   444  # IF YOU USE THIS TO DELIVER MAIL SYSTEM-WIDE, YOU MUST SET UP AN
   445  # ALIAS THAT FORWARDS MAIL FOR ROOT TO A REAL USER.
   446  #
   447  #mailbox_command = /some/where/procmail
   448  #mailbox_command = /some/where/procmail -a "$EXTENSION"
   449
   450  # The mailbox_transport specifies the optional transport in master.cf
   451  # to use after processing aliases and .forward files. This parameter
   452  # has precedence over the mailbox_command, fallback_transport and
   453  # luser_relay parameters.
   454  #
   455  # Specify a string of the form transport:nexthop, where transport is
   456  # the name of a mail delivery transport defined in master.cf.  The
   457  # :nexthop part is optional. For more details see the sample transport
   458  # configuration file.
   459  #
   460  # NOTE: if you use this feature for accounts not in the UNIX password
   461  # file, then you must update the "local_recipient_maps" setting in
   462  # the main.cf file, otherwise the SMTP server will reject mail for    
   463  # non-UNIX accounts with "User unknown in local recipient table".
   464  #
   465  #mailbox_transport = lmtp:unix:/var/lib/imap/socket/lmtp
   466
   467  # If using the cyrus-imapd IMAP server deliver local mail to the IMAP
   468  # server using LMTP (Local Mail Transport Protocol), this is prefered
   469  # over the older cyrus deliver program by setting the
   470  # mailbox_transport as below:
   471  #
   472  # mailbox_transport = lmtp:unix:/var/lib/imap/socket/lmtp
   473  #
   474  # The efficiency of LMTP delivery for cyrus-imapd can be enhanced via
   475  # these settings.
   476  #
   477  # local_destination_recipient_limit = 300
   478  # local_destination_concurrency_limit = 5
   479  #
   480  # Of course you should adjust these settings as appropriate for the
   481  # capacity of the hardware you are using. The recipient limit setting
   482  # can be used to take advantage of the single instance message store
   483  # capability of Cyrus. The concurrency limit can be used to control
   484  # how many simultaneous LMTP sessions will be permitted to the Cyrus
   485  # message store.
   486  #
   487  # To use the old cyrus deliver program you have to set:
   488  #mailbox_transport = cyrus
   489
   490  # The fallback_transport specifies the optional transport in master.cf
   491  # to use for recipients that are not found in the UNIX passwd database.
   492  # This parameter has precedence over the luser_relay parameter.
   493  #
   494  # Specify a string of the form transport:nexthop, where transport is
   495  # the name of a mail delivery transport defined in master.cf.  The
   496  # :nexthop part is optional. For more details see the sample transport
   497  # configuration file.
   498  #
   499  # NOTE: if you use this feature for accounts not in the UNIX password
   500  # file, then you must update the "local_recipient_maps" setting in
   501  # the main.cf file, otherwise the SMTP server will reject mail for    
   502  # non-UNIX accounts with "User unknown in local recipient table".
   503  #
   504  #fallback_transport = lmtp:unix:/var/lib/imap/socket/lmtp
   505  #fallback_transport =
   506
   507  # The luser_relay parameter specifies an optional destination address
   508  # for unknown recipients.  By default, mail for unknown@$mydestination,
   509  # unknown@[$inet_interfaces] or unknown@[$proxy_interfaces] is returned
   510  # as undeliverable.
   511  #
   512  # The following expansions are done on luser_relay: $user (recipient
   513  # username), $shell (recipient shell), $home (recipient home directory),
   514  # $recipient (full recipient address), $extension (recipient address
   515  # extension), $domain (recipient domain), $local (entire recipient
   516  # localpart), $recipient_delimiter. Specify ${name?value} or
   517  # ${name:value} to expand value only when $name does (does not) exist.
   518  #
   519  # luser_relay works only for the default Postfix local delivery agent.
   520  #
   521  # NOTE: if you use this feature for accounts not in the UNIX password
   522  # file, then you must specify "local_recipient_maps =" (i.e. empty) in
   523  # the main.cf file, otherwise the SMTP server will reject mail for    
   524  # non-UNIX accounts with "User unknown in local recipient table".
   525  #
   526  #luser_relay = $user@other.host
   527  #luser_relay = $local@other.host
   528  #luser_relay = admin+$local
   529    
   530  # JUNK MAIL CONTROLS
   531  #
   532  # The controls listed here are only a very small subset. The file
   533  # SMTPD_ACCESS_README provides an overview.
   534
   535  # The header_checks parameter specifies an optional table with patterns
   536  # that each logical message header is matched against, including
   537  # headers that span multiple physical lines.
   538  #
   539  # By default, these patterns also apply to MIME headers and to the
   540  # headers of attached messages. With older Postfix versions, MIME and
   541  # attached message headers were treated as body text.
   542  #
   543  # For details, see "man header_checks".
   544  #
   545  #header_checks = regexp:/etc/postfix/header_checks
   546
   547  # FAST ETRN SERVICE
   548  #
   549  # Postfix maintains per-destination logfiles with information about
   550  # deferred mail, so that mail can be flushed quickly with the SMTP
   551  # "ETRN domain.tld" command, or by executing "sendmail -qRdomain.tld".
   552  # See the ETRN_README document for a detailed description.
   553  #
   554  # The fast_flush_domains parameter controls what destinations are
   555  # eligible for this service. By default, they are all domains that
   556  # this server is willing to relay mail to.
   557  #
   558  #fast_flush_domains = $relay_domains
   559
   560  # SHOW SOFTWARE VERSION OR NOT
   561  #
   562  # The smtpd_banner parameter specifies the text that follows the 220
   563  # code in the SMTP server‘s greeting banner. Some people like to see
   564  # the mail version advertised. By default, Postfix shows no version.
   565  #
   566  # You MUST specify $myhostname at the start of the text. That is an
   567  # RFC requirement. Postfix itself does not care.
   568  #
   569  #smtpd_banner = $myhostname ESMTP $mail_name
   570  #smtpd_banner = $myhostname ESMTP $mail_name ($mail_version)
   571
   572  # PARALLEL DELIVERY TO THE SAME DESTINATION
   573  #
   574  # How many parallel deliveries to the same user or domain? With local
   575  # delivery, it does not make sense to do massively parallel delivery
   576  # to the same user, because mailbox updates must happen sequentially,
   577  # and expensive pipelines in .forward files can cause disasters when
   578  # too many are run at the same time. With SMTP deliveries, 10
   579  # simultaneous connections to the same domain could be sufficient to
   580  # raise eyebrows.
   581  #
   582  # Each message delivery transport has its XXX_destination_concurrency_limit
   583  # parameter.  The default is $default_destination_concurrency_limit for
   584  # most delivery transports. For the local delivery agent the default is 2.
   585
   586  #local_destination_concurrency_limit = 2
   587  #default_destination_concurrency_limit = 20
   588
   589  # DEBUGGING CONTROL
   590  #
   591  # The debug_peer_level parameter specifies the increment in verbose
   592  # logging level when an SMTP client or server host name or address
   593  # matches a pattern in the debug_peer_list parameter.
   594  #
   595  debug_peer_level = 2
   596
   597  # The debug_peer_list parameter specifies an optional list of domain
   598  # or network patterns, /file/name patterns or type:name tables. When
   599  # an SMTP client or server host name or address matches a pattern,
   600  # increase the verbose logging level by the amount specified in the
   601  # debug_peer_level parameter.
   602  #
   603  #debug_peer_list = 127.0.0.1
   604  #debug_peer_list = some.domain
   605
   606  # The debugger_command specifies the external command that is executed
   607  # when a Postfix daemon program is run with the -D option.
   608  #
   609  # Use "command .. & sleep 5" so that the debugger can attach before
   610  # the process marches on. If you use an X-based debugger, be sure to
   611  # set up your XAUTHORITY environment variable before starting Postfix.
   612  #
   613  debugger_command =
   614           PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
   615           ddd $daemon_directory/$process_name $process_id & sleep 5
   616
   617  # If you can‘t use X, use this to capture the call stack when a
   618  # daemon crashes. The result is in a file in the configuration
   619  # directory, and is named after the process name and the process ID.
   620  #
   621  # debugger_command =
   622  #       PATH=/bin:/usr/bin:/usr/local/bin; export PATH; (echo cont;
   623  #       echo where) | gdb $daemon_directory/$process_name $process_id 2>&1
   624  #       >$config_directory/$process_name.$process_id.log & sleep 5
   625  #
   626  # Another possibility is to run gdb under a detached screen session.
   627  # To attach to the screen sesssion, su root and run "screen -r
   628  # <id_string>" where <id_string> uniquely matches one of the detached
   629  # sessions (from "screen -list").
   630  #
   631  # debugger_command =
   632  #       PATH=/bin:/usr/bin:/sbin:/usr/sbin; export PATH; screen
   633  #       -dmS $process_name gdb $daemon_directory/$process_name
   634  #       $process_id & sleep 1
   635
   636  # INSTALL-TIME CONFIGURATION INFORMATION
   637  #
   638  # The following parameters are used when installing a new Postfix version.
   639  #
   640  # sendmail_path: The full pathname of the Postfix sendmail command.
   641  # This is the Sendmail-compatible mail posting interface.
   642  #
   643  sendmail_path = /usr/sbin/sendmail.postfix
   644
   645  # newaliases_path: The full pathname of the Postfix newaliases command.
   646  # This is the Sendmail-compatible command to build alias databases.
   647  #
   648  newaliases_path = /usr/bin/newaliases.postfix
   649
   650  # mailq_path: The full pathname of the Postfix mailq command.  This
   651  # is the Sendmail-compatible mail queue listing command.
   652  #
   653  mailq_path = /usr/bin/mailq.postfix
   654
   655  # setgid_group: The group for mail submission and queue management
   656  # commands.  This must be a group name with a numerical group ID that
   657  # is not shared with other accounts, not even with the Postfix account.
   658  #
   659  setgid_group = postdrop
   660
   661  # html_directory: The location of the Postfix HTML documentation.
   662  #
   663  html_directory = no
   664
   665  # manpage_directory: The location of the Postfix on-line manual pages.
   666  #
   667  manpage_directory = /usr/share/man
   668
   669  # sample_directory: The location of the Postfix sample configuration files.
   670  # This parameter is obsolete as of Postfix 2.1.
   671  #
   672  sample_directory = /usr/share/doc/postfix-2.6.6/samples
   673
   674  # readme_directory: The location of the Postfix README files.
   675  #
   676  readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES

/etc/postfix/main.cf