{
    "mode": "man",
    "parameter": "VIRTUAL",
    "section": "8postfix",
    "url": "https://www.chedong.com/phpMan.php/man/VIRTUAL/8postfix/json",
    "generated": "2026-08-14T03:46:36Z",
    "synopsis": "virtual [generic Postfix daemon options]",
    "sections": {
        "NAME": {
            "content": "virtual - Postfix virtual domain mail delivery agent\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "virtual [generic Postfix daemon options]\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "The virtual(8) delivery agent is designed for virtual mail hosting services. Originally based\non  the  Postfix  local(8) delivery agent, this agent looks up recipients with map lookups of\ntheir full recipient address, instead of using hard-coded unix password file lookups  of  the\naddress local part only.\n\nThis  delivery  agent only delivers mail.  Other features such as mail forwarding, out-of-of‐\nfice notifications, etc., must be configured via virtualalias maps  or  via  similar  lookup\nmechanisms.\n",
            "subsections": []
        },
        "MAILBOX LOCATION": {
            "content": "The  mailbox location is controlled by the virtualmailboxbase and virtualmailboxmaps con‐\nfiguration parameters (see below).  The virtualmailboxmaps table is indexed by the  recipi‐\nent address as described under TABLE SEARCH ORDER below.\n\nThe mailbox pathname is constructed as follows:\n\n$virtualmailboxbase/$virtualmailboxmaps(recipient)\n\nwhere recipient is the full recipient address.\n",
            "subsections": []
        },
        "UNIX MAILBOX FORMAT": {
            "content": "When the mailbox location does not end in /, the message is delivered in UNIX mailbox format.\nThis format stores multiple messages in one textfile.\n\nThe  virtual(8)  delivery  agent  prepends a \"From sender timestamp\" envelope header to each\nmessage, prepends a  Delivered-To:  message  header  with  the  envelope  recipient  address,\nprepends  an X-Original-To: header with the recipient address as given to Postfix, prepends a\nReturn-Path: message header with the envelope sender address, prepends a > character to lines\nbeginning with \"From \", and appends an empty line.\n\nThe mailbox is locked for exclusive access while delivery is in progress. In  case  of  prob‐\nlems, an attempt is made to truncate the mailbox to its original length.\n",
            "subsections": []
        },
        "QMAIL MAILDIR FORMAT": {
            "content": "When  the  mailbox location ends in /, the message is delivered in qmail maildir format. This\nformat stores one message per file.\n\nThe virtual(8) delivery agent prepends a Delivered-To: message header with the final envelope\nrecipient address, prepends an X-Original-To: header with the recipient address as  given  to\nPostfix, and prepends a Return-Path: message header with the envelope sender address.\n\nBy definition, maildir format does not require application-level file locking during mail de‐\nlivery or retrieval.\n",
            "subsections": []
        },
        "MAILBOX OWNERSHIP": {
            "content": "Mailbox  ownership  is controlled by the virtualuidmaps and virtualgidmaps lookup tables,\nwhich are indexed with the full recipient address. Each table provides a string with the  nu‐\nmerical user and group ID, respectively.\n\nThe  virtualminimumuid parameter imposes a lower bound on numerical user ID values that may\nbe specified in any virtualuidmaps.\n",
            "subsections": []
        },
        "CASE FOLDING": {
            "content": "All delivery decisions are made using the full recipient address, folded to lower  case.  See\nalso the next section for a few exceptions with optional address extensions.\n",
            "subsections": []
        },
        "TABLE SEARCH ORDER": {
            "content": "Normally,  a  lookup table is specified as a text file that serves as input to the postmap(1)\ncommand. The result, an indexed file in dbm or db format, is used for fast searching  by  the\nmail system.\n\nThe search order is as follows. The search stops upon the first successful lookup.\n\n•      When the recipient has an optional address extension the user+extension@domain.tld ad‐\ndress is looked up first.\n\nWith Postfix versions before 2.1, the optional address extension is always ignored.\n\n•      The user@domain.tld address, without address extension, is looked up next.\n\n•      Finally, the recipient @domain is looked up.\n\nWhen  the  table  is  provided via other means such as NIS, LDAP or SQL, the same lookups are\ndone as for ordinary indexed files.\n\nAlternatively, a table can be provided as a regular-expression map where patterns  are  given\nas  regular  expressions. In that case, only the full recipient address is given to the regu‐\nlar-expression map.\n",
            "subsections": []
        },
        "SECURITY": {
            "content": "The virtual(8) delivery agent is not security sensitive, provided that the lookup tables with\nrecipient user/group ID information are adequately protected. This program is not designed to\nrun chrooted.\n\nThe virtual(8) delivery agent disallows regular expression substitution of $1 etc. in regular\nexpression lookup tables, because that would open a security hole.\n\nThe virtual(8) delivery agent will silently ignore requests to use  the  proxymap(8)  server.\nInstead  it  will  open  the table directly. Before Postfix version 2.2, the virtual delivery\nagent will terminate with a fatal error.\n",
            "subsections": []
        },
        "STANDARDS": {
            "content": "RFC 822 (ARPA Internet Text Messages)\n",
            "subsections": []
        },
        "DIAGNOSTICS": {
            "content": "Mail bounces when the recipient has no mailbox or when the recipient is over disk  quota.  In\nall other problem cases, mail for an existing recipient is deferred and a warning is logged.\n\nProblems  and  transactions are logged to syslogd(8) or postlogd(8).  Corrupted message files\nare marked so that the queue manager can move them to the corrupt queue afterwards.\n\nDepending on the setting of the notifyclasses  parameter,  the  postmaster  is  notified  of\nbounces and of other trouble.\n",
            "subsections": []
        },
        "BUGS": {
            "content": "This  delivery agent supports address extensions in email addresses and in lookup table keys,\nbut does not propagate address extension information to the result of table lookup.\n\nPostfix should have lookup tables that can return multiple result  attributes.  In  order  to\navoid the inconvenience of maintaining three tables, use an LDAP or MYSQL database.\n",
            "subsections": []
        },
        "CONFIGURATION PARAMETERS": {
            "content": "Changes  to  main.cf are picked up automatically, as virtual(8) processes run for only a lim‐\nited amount of time. Use the command \"postfix reload\" to speed up a change.\n\nThe text below provides only a parameter summary. See postconf(5) for more details  including\nexamples.\n",
            "subsections": []
        },
        "MAILBOX DELIVERY CONTROLS": {
            "content": "",
            "subsections": [
                {
                    "name": "virtual_mailbox_base (empty)",
                    "content": "A  prefix  that  the  virtual(8)  delivery agent prepends to all pathname results from\n$virtualmailboxmaps table lookups.\n"
                },
                {
                    "name": "virtual_mailbox_maps (empty)",
                    "content": "Optional lookup tables with all valid  addresses  in  the  domains  that  match  $vir‐\ntualmailboxdomains.\n"
                },
                {
                    "name": "virtual_minimum_uid (100)",
                    "content": "The  minimum user ID value that the virtual(8) delivery agent accepts as a result from\n$virtualuidmaps table lookup.\n"
                },
                {
                    "name": "virtual_uid_maps (empty)",
                    "content": "Lookup tables with the per-recipient user ID that the virtual(8) delivery  agent  uses\nwhile writing to the recipient's mailbox.\n"
                },
                {
                    "name": "virtual_gid_maps (empty)",
                    "content": "Lookup tables with the per-recipient group ID for virtual(8) mailbox delivery.\n\nAvailable in Postfix version 2.0 and later:\n"
                },
                {
                    "name": "virtual_mailbox_domains ($virtual_mailbox_maps)",
                    "content": "Postfix  is the final destination for the specified list of domains; mail is delivered\nvia the $virtualtransport mail delivery transport.\n"
                },
                {
                    "name": "virtual_transport (virtual)",
                    "content": "The default mail delivery transport and next-hop destination for final delivery to do‐\nmains listed with $virtualmailboxdomains.\n\nAvailable in Postfix version 2.5.3 and later:\n"
                },
                {
                    "name": "strict_mailbox_ownership (yes)",
                    "content": "Defer delivery when a mailbox file is not owned by its recipient.\n"
                }
            ]
        },
        "LOCKING CONTROLS": {
            "content": "",
            "subsections": [
                {
                    "name": "virtual_mailbox_lock (see 'postconf -d' output)",
                    "content": "How to lock a UNIX-style virtual(8) mailbox before attempting delivery.\n"
                },
                {
                    "name": "deliver_lock_attempts (20)",
                    "content": "The maximal number of attempts to acquire an exclusive  lock  on  a  mailbox  file  or\nbounce(8) logfile.\n"
                },
                {
                    "name": "deliver_lock_delay (1s)",
                    "content": "The  time between attempts to acquire an exclusive lock on a mailbox file or bounce(8)\nlogfile.\n"
                },
                {
                    "name": "stale_lock_time (500s)",
                    "content": "The time after which a stale exclusive mailbox lockfile is removed.\n"
                }
            ]
        },
        "RESOURCE AND RATE CONTROLS": {
            "content": "",
            "subsections": [
                {
                    "name": "virtual_mailbox_limit (51200000)",
                    "content": "The maximal size in bytes of an individual virtual(8) mailbox or maildir file, or zero\n(no limit).\n\nImplemented in the qmgr(8) daemon:\n"
                },
                {
                    "name": "virtual_destination_concurrency_limit ($default_destination_concurrency_limit)",
                    "content": "The maximal number of parallel deliveries to the same destination via the virtual mes‐\nsage delivery transport.\n"
                },
                {
                    "name": "virtual_destination_recipient_limit ($default_destination_recipient_limit)",
                    "content": "The maximal number of recipients per message for the virtual message  delivery  trans‐\nport.\n"
                }
            ]
        },
        "MISCELLANEOUS CONTROLS": {
            "content": "",
            "subsections": [
                {
                    "name": "config_directory (see 'postconf -d' output)",
                    "content": "The default location of the Postfix main.cf and master.cf configuration files.\n"
                },
                {
                    "name": "daemon_timeout (18000s)",
                    "content": "How  much time a Postfix daemon process may take to handle a request before it is ter‐\nminated by a built-in watchdog timer.\n"
                },
                {
                    "name": "delay_logging_resolution_limit (2)",
                    "content": "The maximal number of digits after the decimal point  when  logging  sub-second  delay\nvalues.\n"
                },
                {
                    "name": "ipc_timeout (3600s)",
                    "content": "The  time  limit  for  sending or receiving information over an internal communication\nchannel.\n"
                },
                {
                    "name": "max_idle (100s)",
                    "content": "The maximum amount of time that an idle Postfix daemon process waits for  an  incoming\nconnection before terminating voluntarily.\n"
                },
                {
                    "name": "max_use (100)",
                    "content": "The  maximal number of incoming connections that a Postfix daemon process will service\nbefore terminating voluntarily.\n"
                },
                {
                    "name": "process_id (read-only)",
                    "content": "The process ID of a Postfix command or daemon process.\n"
                },
                {
                    "name": "process_name (read-only)",
                    "content": "The process name of a Postfix command or daemon process.\n"
                },
                {
                    "name": "queue_directory (see 'postconf -d' output)",
                    "content": "The location of the Postfix top-level queue directory.\n"
                },
                {
                    "name": "syslog_facility (mail)",
                    "content": "The syslog facility of Postfix logging.\n"
                },
                {
                    "name": "syslog_name (see 'postconf -d' output)",
                    "content": "A prefix that is prepended to the process name in syslog records, so that,  for  exam‐\nple, \"smtpd\" becomes \"prefix/smtpd\".\n\nAvailable in Postfix version 3.0 and later:\n"
                },
                {
                    "name": "virtual_delivery_status_filter ($default_delivery_status_filter)",
                    "content": "Optional  filter  for the virtual(8) delivery agent to change the delivery status code\nor explanatory text of successful or unsuccessful deliveries.\n\nAvailable in Postfix version 3.3 and later:\n"
                },
                {
                    "name": "enable_original_recipient (yes)",
                    "content": "Enable support for the original recipient address after an address is rewritten  to  a\ndifferent address (for example with aliasing or with canonical mapping).\n"
                },
                {
                    "name": "service_name (read-only)",
                    "content": "The master.cf service name of a Postfix daemon process.\n\nAvailable in Postfix 3.5 and later:\n"
                },
                {
                    "name": "info_log_address_format (external)",
                    "content": "The email address form that will be used in non-debug logging (info, warning, etc.).\n"
                }
            ]
        },
        "SEE ALSO": {
            "content": "qmgr(8), queue manager\nbounce(8), delivery status reports\npostconf(5), configuration parameters\npostlogd(8), Postfix logging\nsyslogd(8), system logging\n",
            "subsections": []
        },
        "READMEFILES": {
            "content": "Use \"postconf readmedirectory\" or\n\"postconf htmldirectory\" to locate this information.\nVIRTUALREADME, domain hosting howto\n",
            "subsections": []
        },
        "LICENSE": {
            "content": "The Secure Mailer license must be distributed with this software.\n",
            "subsections": []
        },
        "HISTORY": {
            "content": "This  delivery  agent was originally based on the Postfix local delivery agent. Modifications\nmainly consisted of removing code that either was not applicable or that was not safe in this\ncontext: aliases, ~user/.forward files, delivery to \"|command\" or to /file/name.\n\nThe Delivered-To: message header appears in the qmail system by Daniel Bernstein.\n\nThe maildir structure appears in the qmail system by Daniel Bernstein.\n\nAUTHOR(S)\nWietse Venema\nIBM T.J. Watson Research\nP.O. Box 704\nYorktown Heights, NY 10598, USA\n\nWietse Venema\nGoogle, Inc.\n111 8th Avenue\nNew York, NY 10011, USA\n\nAndrew McNamara\nandrewm@connect.com.au\nconnect.com.au Pty. Ltd.\nLevel 3, 213 Miller St\nNorth Sydney 2060, NSW, Australia\n\nVIRTUAL(8postfix)",
            "subsections": []
        }
    },
    "summary": "virtual - Postfix virtual domain mail delivery agent",
    "flags": [],
    "examples": [],
    "see_also": [
        {
            "name": "qmgr",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/qmgr/8/json"
        },
        {
            "name": "bounce",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/bounce/8/json"
        },
        {
            "name": "postconf",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/postconf/5/json"
        },
        {
            "name": "postlogd",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/postlogd/8/json"
        },
        {
            "name": "syslogd",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/syslogd/8/json"
        }
    ]
}