{ "mode": "man", "parameter": "virtual", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/virtual/8/json", "generated": "2026-06-10T16:07:38Z", "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 $1 etc. in regular\nexpression lookup tables, because that would open a security hole.\n\nThe virtual(8) delivery agent will silently ignore requests to use the proxymap(8) server.\nInstead it will open the table directly. Before Postfix version 2.2, the virtual delivery\nagent will terminate with a fatal error.\n", "subsections": [] }, "STANDARDS": { "content": "RFC 822 (ARPA Internet Text Messages)\n", "subsections": [] }, "DIAGNOSTICS": { "content": "Mail bounces when the recipient has no mailbox or when the recipient is over disk quota. In\nall other cases, mail for an existing recipient is deferred and a warning is logged.\n\nProblems and transactions are logged to syslogd(8) or postlogd(8). Corrupted message files\nare marked so that the queue manager can move them to the corrupt queue afterwards.\n\nDepending on the setting of the notifyclasses parameter, the postmaster is notified of\nbounces and of other trouble.\n", "subsections": [] }, "BUGS": { "content": "This delivery agent supports address extensions in email addresses and in lookup table keys,\nbut does not propagate address extension information to the result of table lookup.\n\nPostfix should have lookup tables that can return multiple result attributes. In order to\navoid the inconvenience of maintaining three tables, use an LDAP or MYSQL database.\n", "subsections": [] }, "CONFIGURATION PARAMETERS": { "content": "Changes to main.cf are picked up automatically, as virtual(8) processes run for only a lim‐\nited amount of time. Use the command \"postfix reload\" to speed up a change.\n\nThe text below provides only a parameter summary. See postconf(5) for more details including\nexamples.\n", "subsections": [] }, "MAILBOX DELIVERY CONTROLS": { "content": "virtualmailboxbase (empty)\nA prefix that the virtual(8) delivery agent prepends to all pathname results from\n$virtualmailboxmaps table lookups.\n\nvirtualmailboxmaps (empty)\nOptional lookup tables with all valid addresses in the domains that match $vir‐\ntualmailboxdomains.\n\nvirtualminimumuid (100)\nThe minimum user ID value that the virtual(8) delivery agent accepts as a result from\n$virtualuidmaps table lookup.\n\nvirtualuidmaps (empty)\nLookup tables with the per-recipient user ID that the virtual(8) delivery agent uses\nwhile writing to the recipient's mailbox.\n\nvirtualgidmaps (empty)\nLookup tables with the per-recipient group ID for virtual(8) mailbox delivery.\n\nAvailable in Postfix version 2.0 and later:\n\nvirtualmailboxdomains ($virtualmailboxmaps)\nPostfix is final destination for the specified list of domains; mail is delivered via\nthe $virtualtransport mail delivery transport.\n\nvirtualtransport (virtual)\nThe default mail delivery transport and next-hop destination for final delivery to do‐\nmains listed with $virtualmailboxdomains.\n\nAvailable in Postfix version 2.5.3 and later:\n\nstrictmailboxownership (yes)\nDefer delivery when a mailbox file is not owned by its recipient.\n", "subsections": [] }, "LOCKING CONTROLS": { "content": "virtualmailboxlock (see 'postconf -d' output)\nHow to lock a UNIX-style virtual(8) mailbox before attempting delivery.\n\ndeliverlockattempts (20)\nThe maximal number of attempts to acquire an exclusive lock on a mailbox file or\nbounce(8) logfile.\n\ndeliverlockdelay (1s)\nThe time between attempts to acquire an exclusive lock on a mailbox file or bounce(8)\nlogfile.\n\nstalelocktime (500s)\nThe time after which a stale exclusive mailbox lockfile is removed.\n", "subsections": [] }, "RESOURCE AND RATE CONTROLS": { "content": "virtualmailboxlimit (51200000)\nThe maximal size in bytes of an individual virtual(8) mailbox or maildir file, or zero\n(no limit).\n\nImplemented in the qmgr(8) daemon:\n\nvirtualdestinationconcurrencylimit ($defaultdestinationconcurrencylimit)\nThe maximal number of parallel deliveries to the same destination via the virtual mes‐\nsage delivery transport.\n\nvirtualdestinationrecipientlimit ($defaultdestinationrecipientlimit)\nThe maximal number of recipients per message for the virtual message delivery trans‐\nport.\n", "subsections": [] }, "MISCELLANEOUS CONTROLS": { "content": "configdirectory (see 'postconf -d' output)\nThe default location of the Postfix main.cf and master.cf configuration files.\n\ndaemontimeout (18000s)\nHow much time a Postfix daemon process may take to handle a request before it is ter‐\nminated by a built-in watchdog timer.\n\ndelayloggingresolutionlimit (2)\nThe maximal number of digits after the decimal point when logging sub-second delay\nvalues.\n\nipctimeout (3600s)\nThe time limit for sending or receiving information over an internal communication\nchannel.\n\nmaxidle (100s)\nThe maximum amount of time that an idle Postfix daemon process waits for an incoming\nconnection before terminating voluntarily.\n\nmaxuse (100)\nThe maximal number of incoming connections that a Postfix daemon process will service\nbefore terminating voluntarily.\n\nprocessid (read-only)\nThe process ID of a Postfix command or daemon process.\n\nprocessname (read-only)\nThe process name of a Postfix command or daemon process.\n\nqueuedirectory (see 'postconf -d' output)\nThe location of the Postfix top-level queue directory.\n\nsyslogfacility (mail)\nThe syslog facility of Postfix logging.\n\nsyslogname (see 'postconf -d' output)\nA prefix that is prepended to the process name in syslog records, so that, for exam‐\nple, \"smtpd\" becomes \"prefix/smtpd\".\n\nAvailable in Postfix version 3.0 and later:\n\nvirtualdeliverystatusfilter ($defaultdeliverystatusfilter)\nOptional 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\nenableoriginalrecipient (yes)\nEnable support for the original recipient address after an address is rewritten to a\ndifferent address (for example with aliasing or with canonical mapping).\n\nservicename (read-only)\nThe master.cf service name of a Postfix daemon process.\n\nAvailable in Postfix 3.5 and later:\n\ninfologaddressformat (external)\nThe email address form that will be used in non-debug logging (info, warning, etc.).\n", "subsections": [] }, "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\n\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" } ] }