Ошибка recipient address rejected user unknown in virtual mailbox table

Everyone expects their emails to work perfectly, but that doesn’t always work.

Sometimes, emails bounce with strange errors. And, one such error is “user unknown in virtual mailbox table” in Postfix servers.

What’s this virtual mailbox table? How can I add the user in this table? Many of these questions may arise in your mind.

At Bobcares, we help server owners resolve such complex email errors as part of our Server Management Services.

Today, we’ll discuss the top 4 reasons for this error and how we fix them.

“User unknown in virtual mailbox table” in Postfix – What this error means?

This is one of the common errors in Postifx mail servers when users send emails to their local mailboxes. The exact bounce message looks like this:

[postfix]550 ..: Recipient address rejected: User unknown in virtual mailbox table

So, here our Support Experts check the Postfix email logs(/var/log/maillog) to find the origin of the problem. For instance, the email logs shows the error message like this:

postfix/smtpd[14568]: NOQUEUE: reject: RCPT from domain.com[1xx.15x.12x.3]: 550 5.1.1 <test@example.com>: Recipient address rejected: User unknown in virtual mailbox table; from=<postmaster@domain.com> to=<test@example.com> proto=ESMTP helo=<domain.com>

This error message shows that emails are not delivered to the mailbox test@example.com. Because, the mail server can’t find this email account on the server.

In other words for the emails to work properly, the mail server must know the exact mail delivery path of a domain. If the exact email delivery path of the domain can’t be found, it throws this error.

“User unknown in virtual mailbox table” in Postfix – Causes & Fixes

Now, we’ve a clear understanding of this error. Let’s now discuss the main reasons for this error and how our Support Engineers fix them.

1)Typo in Recipient address

If the recipient mail server can’t find the recipient email account, it would throw the error “User unknown in virtual mailbox table” in Postfix. In other words, a typo in the email address like extra space, dot, missing alphabet, etc. can lead to this error.

Similarly, there are instances where an email account existed on the server got removed or disabled by the customer, or it may moved to another server. In such cases, the recipient server can’t route the emails.

How we fix?

Firstly, our Support Engineers confirm that there are no typo errors in the email address given by the customer. Also, we confirm that the email account is a valid one.

For example in Plesk Postifix servers, we use the below command to check if the email accounts exists or not.

postmap -s /var/spool/postfix/plesk/vmailbox | grep test@example.com

If not, we’ll manually add the email account under the domain. In addition to that, we check the DNS connectivity of the domain using tools such as dig, traceroute, etc. and confirm that the domain resolves to the correct server.

2) Email routing issues

The email delivery path can be either Local(mailbox within in the server) or Remote(mailbox outside the server). That is, emails are delivered outside the server if the email delivery path is set as remote.

Most mail servers offer the option of specifying the mail delivery path of the domains. But, misconfiguration in the Email routing of these domains can also lead to error.

For example, consider the domain example.com that uses remote mail server Gmail. But, if the Email Routing is set to Local, the mail server tries to treat the domain example.com as local. However, there are no mailboxes on the server. As a result, the mail server rejects the email with error “User unknown in virtual mailbox table“.

How we fix?

Firstly, our Support Specialists check the MX records of the recipient domain using the dig command.

dig example.com MX

If the email service of the domain is handled remotely, we’ll disable the email service on the local server to ensure that the email works fine. For example in Plesk servers, we disable the email service of a domain using the below command.

plesk bin mail --off example.com

Likewise in Postfix servers, we modify the mydestination parameter in the Postfix configuration file /etc/postfix/main.cf to ensure that the server only handles emails for the intended domains.

Most importantly, we make sure to backup the Postfix configuration file before making these changes.

[And, do you need help in fixing this error? Our Support Experts can fix it for you.]

3) Bad DNS records

Similarly, “user unknown in virtual mailbox table” error can occur when the MX records of the domain aren’t resolving or the MX record of the domain doesn’t point to the correct server.

We’ve seen instances where the domain holds wrong MX entries after domain migration, IP address switches, etc. In such cases, recipient mail server can’t find the domain on the server and reject the emails.

How we fix?

Our Support Engineers verify the MX records of the domain using the below command.

dig domain.com MX

And, if we notice missing MX entries or DNS errors, then we correct the DNS entries of the domain to get it fixed.

4) Corrupted Mail server configuration

Moreover, the configuration mistakes on the mail server such as SMTP settings, SSL settings, etc. can also lead to this error.

For example in Plesk Postfix servers, we’ve seen cases where incorrect/invalid entries of a domain in the /var/spool/postfix/plesk/virtual file result in this error.

How we fix?

Our Hosting Engineers check the validity of the domain entries in the mail server configuration files. For example, in Postfix servers, we use the following command to see if the domain is properly added in the /var/spool/postfix/plesk/virtual file.

postmap -s /var/spool/postfix/plesk/virtual | grep example.com

If the domain is missing, we backup this file and add the domain to this virtual.db file.

[Messed up mail server configuration? Get one of our Server Experts to look into your issue and fix it for you.]

Conclusion

In short, “user unknown in virtual mailbox table” error in Postfix can occur due to bad DNS records, email routing issues, and more. Today, we’ve discussed the top 4 reasons for this error and how ourSupport Engineers fix them.

var google_conversion_label = «owonCMyG5nEQ0aD71QM»;

I had Migrated exchange 2007 to exchange 2010.

Now not able to recieve mail from outside for newly created mailboxin exch 2010. MX record was pointed to new exchange.

The thing is the mailbox which was migrated from exch 2007 to 2010 are able recieve mail but newly created mailbox in 2010 not recieving mail I
am getting bounce back mail as below.

Delivery to the following recipient failed permanently:

    
administrator@silk-crafts.com

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 5.1.1 <administrator@silk-crafts.com>:
Recipient address rejected: User unknown in virtual mailbox table (state 13).

—— Original message ——

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=mime-version:date:message-id:subject:from:to:content-type;
        bh=+JGsIhSUZQQPVCUhLBWKGtGAESLIXAbzK+0LifBog7c=;
        b=auu7vjTZMflOQmL/2PCd82JyDa2FkucofhGoISTT6QfwFCzlMFnFRALA9/FGsEFNL7
         kJsYQK5vHQNrmLVLZcYao3dCjWyyGi7hv4Ntmlf1VK13n4DgJszbF0kUbFVp/uVXlBtf
         9ykDDJNDNmoUPb1NBbQi10wcfTzyLevOTUZjjjq3KZ9A7VtDorp4q5xReaB2V2bj+ig/
         jw6KIO4xA7ekOc9h2Rpa8p3YIvIKCI3tmIELICXeohC6WrS1+X0y1oFo+IMVLqifROIm
         g1Z9J5oh6WEGrWGl8GxaYw7crnGtq59FMbUrCuyIpaFGysyQOgdsBowoK+1XmN/c0a28
         8hHg==
MIME-Version: 1.0
Received: by 10.60.6.73 with SMTP id y9mr38470930oey.17.1341766088564; Sun, 08
 Jul 2012 09:48:08 -0700 (PDT)
Received: by 10.60.125.3 with HTTP; Sun, 8 Jul 2012 09:48:08 -0700 (PDT)
Date: Sun, 8 Jul 2012 22:18:08 +0530
Message-ID: <CAB4Xy=i7CHHnak6KUwmw1GkMG4tL93A4fwxOTaxBoguZOUGXNw@mail.gmail.com>
Subject: test
From: «Moh@n» <mohan.6968@gmail.com>
To: administrator@silk-crafts.com
Content-Type: multipart/alternative; boundary=e89a8ff25014149f0e04c454431b

Further to thi below is the email dossier detail from two mailbox(Old mailbox which was moved from 2007 to 2010 and newly created mailbox in 2010)

Validating
mohanb@silk-crafts.com…

Validation results

MX records

SMTP session

[Resolving silk-crafts-com.p10.spamhero.com…]
[Contacting silk-crafts-com.p10.spamhero.com [108.60.195.222]…]
[Connected]
220 bolt7a.mxthunder.net ESMTP Postfix
EHLO hexillion.com
250-bolt7a.mxthunder.net
250-PIPELINING
250-SIZE 524288000
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM:<HexValidEmail@hexillion.com>
250 2.1.0 Ok
RCPT TO:<mohanb@silk-crafts.com>
550 5.1.1 <mohanb@silk-crafts.com>: Recipient address rejected: User unknown in virtual mailbox table
[Address has been rejected]
RSET
250 2.0.0 Ok
QUIT
221 2.0.0 Bye
[Connection closed]

For working mailbox

Validating
rs@silk-crafts.com…

Validation results

MX records

SMTP session

[Resolving silk-crafts-com.p10.spamhero.com…]
[Contacting silk-crafts-com.p10.spamhero.com [208.53.48.191]…]
[Connected]
220 bolt7b.mxthunder.net ESMTP Postfix
EHLO hexillion.com
250-bolt7b.mxthunder.net
250-PIPELINING
250-SIZE 524288000
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM:<HexValidEmail@hexillion.com>
250 2.1.0 Ok
RCPT TO:<rs@silk-crafts.com>
250 2.1.5 Ok
RSET
250 2.0.0 Ok
QUIT
221 2.0.0 Bye
[Connection closed]

Any one kidly help on this.

I have centos with postfix in plesk. I have setup a domain and when I send email to the same domain from within webmail the email delivers correctly. When I send email outside of the listed domain to say a work address I get the above error. Its as if the machine tries to deliver it locally, cant find the domain so throws an error. Shouldn’t it deliver the email to external mail systems as well?

Below is my main.cf file:

#soft_bounce = no

# LOCAL PATHNAME INFORMATION
#
# The queue_directory specifies the location of the Postfix queue.
# This is also the root directory of Postfix daemons that run chrooted.
# See the files in examples/chroot-setup for setting up Postfix chroot
# environments on different UNIX systems.
#
queue_directory = /var/spool/postfix

# The command_directory parameter specifies the location of all
# postXXX commands.
#
command_directory = /usr/sbin

# The daemon_directory parameter specifies the location of all Postfix
# daemon programs (i.e. programs listed in the master.cf file). This
# directory must be owned by root.
#
daemon_directory = /usr/libexec/postfix

# The data_directory parameter specifies the location of Postfix-writable
# data files (caches, random numbers). This directory must be owned
# by the mail_owner account (see below).
#
data_directory = /var/lib/postfix

# QUEUE AND PROCESS OWNERSHIP
#
# The mail_owner parameter specifies the owner of the Postfix queue
# and of most Postfix daemon processes.  Specify the name of a user
# account THAT DOES NOT SHARE ITS USER OR GROUP ID WITH OTHER ACCOUNTS
# AND THAT OWNS NO OTHER FILES OR PROCESSES ON THE SYSTEM.  In
# particular, don't specify nobody or daemon. PLEASE USE A DEDICATED
# USER.
#
mail_owner = postfix

# The default_privs parameter specifies the default rights used by
# the local delivery agent for delivery to external file or command.
# These rights are used in the absence of a recipient user context.
# DO NOT SPECIFY A PRIVILEGED USER OR THE POSTFIX OWNER.
#
#default_privs = nobody

# INTERNET HOST AND DOMAIN NAMES
# 
# The myhostname parameter specifies the internet hostname of this
# mail system. The default is to use the fully-qualified domain name
# from gethostname(). $myhostname is used as a default value for many
# other configuration parameters.
#
#myhostname = host.domain.tld
#myhostname = virtual.domain.tld

# The mydomain parameter specifies the local internet domain name.
# The default is to use $myhostname minus the first component.
# $mydomain is used as a default value for many other configuration
# parameters.
#
#mydomain = domain.tld

# SENDING MAIL
# 
# The myorigin parameter specifies the domain that locally-posted
# mail appears to come from. The default is to append $myhostname,
# which is fine for small sites.  If you run a domain with multiple
# machines, you should (1) change this to $mydomain and (2) set up
# a domain-wide alias database that aliases each user to
# user@that.users.mailhost.
#
# For the sake of consistency between sender and recipient addresses,
# myorigin also specifies the default domain name that is appended
# to recipient addresses that have no @domain part.
#
#myorigin = $myhostname
myorigin = $mydomain

# RECEIVING MAIL

# The inet_interfaces parameter specifies the network interface
# addresses that this mail system receives mail on.  By default,
# the software claims all active interfaces on the machine. The
# parameter also controls delivery of mail to user@[ip.address].
#
# See also the proxy_interfaces parameter, for network addresses that
# are forwarded to us via a proxy or network address translator.
#
# Note: you need to stop/start Postfix when this parameter changes.
#
#inet_interfaces = all
#inet_interfaces = $myhostname
#inet_interfaces = $myhostname, localhost
inet_interfaces = all

# Enable IPv4, and IPv6 if supported
inet_protocols = all

# The proxy_interfaces parameter specifies the network interface
# addresses that this mail system receives mail on by way of a
# proxy or network address translation unit. This setting extends
# the address list specified with the inet_interfaces parameter.
#
# You must specify your proxy/NAT addresses when your system is a
# backup MX host for other domains, otherwise mail delivery loops
# will happen when the primary MX host is down.
#
#proxy_interfaces =
#proxy_interfaces = 1.2.3.4


#mydestination = localhost.$mydomain, localhost, localhost.localdomain
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
#mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain, mail.$mydomain, www.$mydomain, ftp.$mydomain


#local_recipient_maps = unix:passwd.byname $alias_maps
#local_recipient_maps = proxy:unix:passwd.byname $alias_maps
#local_recipient_maps =


unknown_local_recipient_reject_code = 550

# TRUST AND RELAY CONTROL


#mynetworks_style = class
mynetworks_style = subnet
#mynetworks_style = host

# Alternatively, you can specify the mynetworks list by hand, in
# which case Postfix ignores the mynetworks_style setting.
#
# Specify an explicit list of network/netmask patterns, where the
# mask specifies the number of bits in the network part of a host
# address.
#
# You can also specify the absolute pathname of a pattern file instead
# of listing the patterns here. Specify type:table for table-based lookups
# (the value on the table right-hand side is not used).
#
mynetworks = 212.48.87.0/24, 127.0.0.0/8
#mynetworks = $config_directory/mynetworks
#mynetworks = hash:/etc/postfix/network_table

# The relay_domains parameter restricts what destinations this system will
# relay mail to.  See the smtpd_recipient_restrictions description in
# postconf(5) for detailed information.
#
# By default, Postfix relays mail
# - from "trusted" clients (IP address matches $mynetworks) to any destination,
# - from "untrusted" clients to destinations that match $relay_domains or
#   subdomains thereof, except addresses with sender-specified routing.
# The default relay_domains value is $mydestination.
# 
# In addition to the above, the Postfix SMTP server by default accepts mail
# that Postfix is final destination for:
# - destinations that match $inet_interfaces or $proxy_interfaces,
# - destinations that match $mydestination
# - destinations that match $virtual_alias_domains,
# - destinations that match $virtual_mailbox_domains.
# These destinations do not need to be listed in $relay_domains.
# 
# Specify a list of hosts or domains, /file/name patterns or type:name
# lookup tables, separated by commas and/or whitespace.  Continue
# long lines by starting the next line with whitespace. A file name
# is replaced by its contents; a type:name table is matched when a
# (parent) domain appears as lookup key.
#
# NOTE: Postfix will not automatically forward mail for domains that
# list this system as their primary or backup MX host. See the
# permit_mx_backup restriction description in postconf(5).
#
relay_domains = 

# INTERNET OR INTRANET

# The relayhost parameter specifies the default host to send mail to
# when no entry is matched in the optional transport(5) table. When
# no relayhost is given, mail is routed directly to the destination.
#
# On an intranet, specify the organizational domain name. If your
# internal DNS uses no MX records, specify the name of the intranet
# gateway host instead.
#
# In the case of SMTP, specify a domain, host, host:port, [host]:port,
# [address] or [address]:port; the form [host] turns off MX lookups.
#
# If you're connected via UUCP, see also the default_transport parameter.
#
#relayhost = $mydomain
#relayhost = [gateway.my.domain]
#relayhost = [mailserver.isp.tld]
#relayhost = uucphost
#relayhost = [an.ip.add.ress]
relayhost =

# REJECTING UNKNOWN RELAY USERS
#
# The relay_recipient_maps parameter specifies optional lookup tables
# with all addresses in the domains that match $relay_domains.
#
# If this parameter is defined, then the SMTP server will reject
# mail for unknown relay users. This feature is off by default.
#
# The right-hand side of the lookup tables is conveniently ignored.
# In the left-hand side, specify an @domain.tld wild-card, or specify
# a user@domain.tld address.
# 
#relay_recipient_maps = hash:/etc/postfix/relay_recipients

# INPUT RATE CONTROL
#
# The in_flow_delay configuration parameter implements mail input
# flow control. This feature is turned on by default, although it
# still needs further development (it's disabled on SCO UNIX due
# to an SCO bug).
# 
# A Postfix process will pause for $in_flow_delay seconds before
# accepting a new message, when the message arrival rate exceeds the
# message delivery rate. With the default 100 SMTP server process
# limit, this limits the mail inflow to 100 messages a second more
# than the number of messages delivered per second.
# 
# Specify 0 to disable the feature. Valid delays are 0..10.
# 
#in_flow_delay = 1s

# ADDRESS REWRITING
#
# The ADDRESS_REWRITING_README document gives information about
# address masquerading or other forms of address rewriting including
# username->Firstname.Lastname mapping.

# ADDRESS REDIRECTION (VIRTUAL DOMAIN)
#
# The VIRTUAL_README document gives information about the many forms
# of domain hosting that Postfix supports.

# "USER HAS MOVED" BOUNCE MESSAGES
#
# See the discussion in the ADDRESS_REWRITING_README document.

# TRANSPORT MAP
#
# See the discussion in the ADDRESS_REWRITING_README document.

# ALIAS DATABASE
#
# The alias_maps parameter specifies the list of alias databases used
# by the local delivery agent. The default list is system dependent.
#
# On systems with NIS, the default is to search the local alias
# database, then the NIS alias database. See aliases(5) for syntax
# details.
# 
# If you change the alias database, run "postalias /etc/aliases" (or
# wherever your system stores the mail alias file), or simply run
# "newaliases" to build the necessary DBM or DB file.
#
# It will take a minute or so before changes become visible.  Use
# "postfix reload" to eliminate the delay.
#
#alias_maps = dbm:/etc/aliases
alias_maps = hash:/etc/aliases, hash:/var/spool/postfix/plesk/aliases
#alias_maps = hash:/etc/aliases, nis:mail.aliases
#alias_maps = netinfo:/aliases

# The alias_database parameter specifies the alias database(s) that
# are built with "newaliases" or "sendmail -bi".  This is a separate
# configuration parameter, because alias_maps (see above) may specify
# tables that are not necessarily all under control by Postfix.
#
#alias_database = dbm:/etc/aliases
#alias_database = dbm:/etc/mail/aliases
alias_database = hash:/etc/aliases
#alias_database = hash:/etc/aliases, hash:/opt/majordomo/aliases

# ADDRESS EXTENSIONS (e.g., user+foo)
#
# The recipient_delimiter parameter specifies the separator between
# user names and address extensions (user+foo). See canonical(5),
# local(8), relocated(5) and virtual(5) for the effects this has on
# aliases, canonical, virtual, relocated and .forward file lookups.
# Basically, the software tries user+foo and .forward+foo before
# trying user and .forward.
#
#recipient_delimiter = +

# DELIVERY TO MAILBOX
#
# The home_mailbox parameter specifies the optional pathname of a
# mailbox file relative to a user's home directory. The default
# mailbox file is /var/spool/mail/user or /var/mail/user.  Specify
# "Maildir/" for qmail-style delivery (the / is required).
#
#home_mailbox = Mailbox
home_mailbox = Maildir/

# The mail_spool_directory parameter specifies the directory where
# UNIX-style mailboxes are kept. The default setting depends on the
# system type.
#
#mail_spool_directory = /var/mail
#mail_spool_directory = /var/spool/mail

# The mailbox_command parameter specifies the optional external
# command to use instead of mailbox delivery. The command is run as
# the recipient with proper HOME, SHELL and LOGNAME environment settings.
# Exception:  delivery for root is done as $default_user.
#
# Other environment variables of interest: USER (recipient username),
# EXTENSION (address extension), DOMAIN (domain part of address),
# and LOCAL (the address localpart).
#
# Unlike other Postfix configuration parameters, the mailbox_command
# parameter is not subjected to $parameter substitutions. This is to
# make it easier to specify shell syntax (see example below).
#
# Avoid shell meta characters because they will force Postfix to run
# an expensive shell process. Procmail alone is expensive enough.
#
# IF YOU USE THIS TO DELIVER MAIL SYSTEM-WIDE, YOU MUST SET UP AN
# ALIAS THAT FORWARDS MAIL FOR ROOT TO A REAL USER.
#
#mailbox_command = /some/where/procmail
#mailbox_command = /some/where/procmail -a "$EXTENSION"

# The mailbox_transport specifies the optional transport in master.cf
# to use after processing aliases and .forward files. This parameter
# has precedence over the mailbox_command, fallback_transport and
# luser_relay parameters.
#
# Specify a string of the form transport:nexthop, where transport is
# the name of a mail delivery transport defined in master.cf.  The
# :nexthop part is optional. For more details see the sample transport
# configuration file.
#
# NOTE: if you use this feature for accounts not in the UNIX password
# file, then you must update the "local_recipient_maps" setting in
# the main.cf file, otherwise the SMTP server will reject mail for    
# non-UNIX accounts with "User unknown in local recipient table".
#
#mailbox_transport = lmtp:unix:/var/lib/imap/socket/lmtp

# If using the cyrus-imapd IMAP server deliver local mail to the IMAP
# server using LMTP (Local Mail Transport Protocol), this is prefered
# over the older cyrus deliver program by setting the
# mailbox_transport as below:
#
# mailbox_transport = lmtp:unix:/var/lib/imap/socket/lmtp
#
# The efficiency of LMTP delivery for cyrus-imapd can be enhanced via
# these settings.
#
# local_destination_recipient_limit = 300
# local_destination_concurrency_limit = 5
#
# Of course you should adjust these settings as appropriate for the
# capacity of the hardware you are using. The recipient limit setting
# can be used to take advantage of the single instance message store
# capability of Cyrus. The concurrency limit can be used to control
# how many simultaneous LMTP sessions will be permitted to the Cyrus
# message store.
#
# To use the old cyrus deliver program you have to set:
#mailbox_transport = cyrus

# The fallback_transport specifies the optional transport in master.cf
# to use for recipients that are not found in the UNIX passwd database.
# This parameter has precedence over the luser_relay parameter.
#
# Specify a string of the form transport:nexthop, where transport is
# the name of a mail delivery transport defined in master.cf.  The
# :nexthop part is optional. For more details see the sample transport
# configuration file.
#
# NOTE: if you use this feature for accounts not in the UNIX password
# file, then you must update the "local_recipient_maps" setting in
# the main.cf file, otherwise the SMTP server will reject mail for    
# non-UNIX accounts with "User unknown in local recipient table".
#
#fallback_transport = lmtp:unix:/var/lib/imap/socket/lmtp
#fallback_transport =

# The luser_relay parameter specifies an optional destination address
# for unknown recipients.  By default, mail for unknown@$mydestination,
# unknown@[$inet_interfaces] or unknown@[$proxy_interfaces] is returned
# as undeliverable.
#
# The following expansions are done on luser_relay: $user (recipient
# username), $shell (recipient shell), $home (recipient home directory),
# $recipient (full recipient address), $extension (recipient address
# extension), $domain (recipient domain), $local (entire recipient
# localpart), $recipient_delimiter. Specify ${name?value} or
# ${name:value} to expand value only when $name does (does not) exist.
#
# luser_relay works only for the default Postfix local delivery agent.
#
# NOTE: if you use this feature for accounts not in the UNIX password
# file, then you must specify "local_recipient_maps =" (i.e. empty) in
# the main.cf file, otherwise the SMTP server will reject mail for    
# non-UNIX accounts with "User unknown in local recipient table".
#
#luser_relay = $user@other.host
#luser_relay = $local@other.host
#luser_relay = admin+$local

# JUNK MAIL CONTROLS
# 
# The controls listed here are only a very small subset. The file
# SMTPD_ACCESS_README provides an overview.

# The header_checks parameter specifies an optional table with patterns
# that each logical message header is matched against, including
# headers that span multiple physical lines.
#
# By default, these patterns also apply to MIME headers and to the
# headers of attached messages. With older Postfix versions, MIME and
# attached message headers were treated as body text.
#
# For details, see "man header_checks".
#
#header_checks = regexp:/etc/postfix/header_checks

# FAST ETRN SERVICE
#
# Postfix maintains per-destination logfiles with information about
# deferred mail, so that mail can be flushed quickly with the SMTP
# "ETRN domain.tld" command, or by executing "sendmail -qRdomain.tld".
# See the ETRN_README document for a detailed description.
# 
# The fast_flush_domains parameter controls what destinations are
# eligible for this service. By default, they are all domains that
# this server is willing to relay mail to.
# 
#fast_flush_domains = $relay_domains

# SHOW SOFTWARE VERSION OR NOT
#
# The smtpd_banner parameter specifies the text that follows the 220
# code in the SMTP server's greeting banner. Some people like to see
# the mail version advertised. By default, Postfix shows no version.
#
# You MUST specify $myhostname at the start of the text. That is an
# RFC requirement. Postfix itself does not care.
#
#smtpd_banner = $myhostname ESMTP $mail_name
#smtpd_banner = $myhostname ESMTP $mail_name ($mail_version)

# PARALLEL DELIVERY TO THE SAME DESTINATION
#
# How many parallel deliveries to the same user or domain? With local
# delivery, it does not make sense to do massively parallel delivery
# to the same user, because mailbox updates must happen sequentially,
# and expensive pipelines in .forward files can cause disasters when
# too many are run at the same time. With SMTP deliveries, 10
# simultaneous connections to the same domain could be sufficient to
# raise eyebrows.
# 
# Each message delivery transport has its XXX_destination_concurrency_limit
# parameter.  The default is $default_destination_concurrency_limit for
# most delivery transports. For the local delivery agent the default is 2.

#local_destination_concurrency_limit = 2
#default_destination_concurrency_limit = 20

# DEBUGGING CONTROL
#
# The debug_peer_level parameter specifies the increment in verbose
# logging level when an SMTP client or server host name or address
# matches a pattern in the debug_peer_list parameter.
#
debug_peer_level = 2

# The debug_peer_list parameter specifies an optional list of domain
# or network patterns, /file/name patterns or type:name tables. When
# an SMTP client or server host name or address matches a pattern,
# increase the verbose logging level by the amount specified in the
# debug_peer_level parameter.
#
#debug_peer_list = 127.0.0.1
#debug_peer_list = some.domain

# The debugger_command specifies the external command that is executed
# when a Postfix daemon program is run with the -D option.
#
# Use "command .. & sleep 5" so that the debugger can attach before
# the process marches on. If you use an X-based debugger, be sure to
# set up your XAUTHORITY environment variable before starting Postfix.
#
debugger_command =
     PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
     ddd $daemon_directory/$process_name $process_id & sleep 5

# If you can't use X, use this to capture the call stack when a
# daemon crashes. The result is in a file in the configuration
# directory, and is named after the process name and the process ID.
#
# debugger_command =
#   PATH=/bin:/usr/bin:/usr/local/bin; export PATH; (echo cont;
#   echo where) | gdb $daemon_directory/$process_name $process_id 2>&1
#   >$config_directory/$process_name.$process_id.log & sleep 5
#
# Another possibility is to run gdb under a detached screen session.
# To attach to the screen sesssion, su root and run "screen -r
# <id_string>" where <id_string> uniquely matches one of the detached
# sessions (from "screen -list").
#
# debugger_command =
#   PATH=/bin:/usr/bin:/sbin:/usr/sbin; export PATH; screen
#   -dmS $process_name gdb $daemon_directory/$process_name
#   $process_id & sleep 1

# INSTALL-TIME CONFIGURATION INFORMATION
#
# The following parameters are used when installing a new Postfix version.
# 
# sendmail_path: The full pathname of the Postfix sendmail command.
# This is the Sendmail-compatible mail posting interface.
# 
sendmail_path = /usr/sbin/sendmail.postfix

# newaliases_path: The full pathname of the Postfix newaliases command.
# This is the Sendmail-compatible command to build alias databases.
#
newaliases_path = /usr/bin/newaliases.postfix

# mailq_path: The full pathname of the Postfix mailq command.  This
# is the Sendmail-compatible mail queue listing command.
# 
mailq_path = /usr/bin/mailq.postfix

# setgid_group: The group for mail submission and queue management
# commands.  This must be a group name with a numerical group ID that
# is not shared with other accounts, not even with the Postfix account.
#
setgid_group = postdrop

# html_directory: The location of the Postfix HTML documentation.
#
html_directory = no

# manpage_directory: The location of the Postfix on-line manual pages.
#
manpage_directory = /usr/share/man

# sample_directory: The location of the Postfix sample configuration files.
# This parameter is obsolete as of Postfix 2.1.
#
sample_directory = /usr/share/doc/postfix-2.8.17/samples

# readme_directory: The location of the Postfix README files.
#
readme_directory = /usr/share/doc/postfix-2.8.17/README_FILES
virtual_mailbox_domains = $virtual_mailbox_maps, hash:/var/spool/postfix/plesk/virtual_domains
virtual_alias_maps = $virtual_maps, hash:/var/spool/postfix/plesk/virtual
virtual_mailbox_maps = , hash:/var/spool/postfix/plesk/vmailbox
transport_maps = , hash:/var/spool/postfix/plesk/transport
smtpd_tls_cert_file = /etc/postfix/postfix_default.pem
smtpd_tls_key_file = $smtpd_tls_cert_file
smtpd_tls_security_level = may
smtpd_use_tls = yes
smtp_tls_security_level = may
smtp_use_tls = no
smtpd_timeout = 3600s
smtpd_proxy_timeout = 3600s
disable_vrfy_command = yes
mynetworks = 127.0.0.0/8
smtpd_sender_restrictions = check_sender_access hash:/var/spool/postfix/plesk/blacklists, permit_sasl_authenticated
smtpd_client_restrictions = permit_mynetworks, permit_sasl_authenticated
smtp_send_xforward_command = yes
smtpd_authorized_xforward_hosts = 127.0.0.0/8
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
virtual_mailbox_base = /var/qmail/mailnames
virtual_uid_maps = static:30
virtual_gid_maps = static:31
smtpd_milters = , inet:127.0.0.1:12768
non_smtpd_milters = 
sender_dependent_default_transport_maps = hash:/var/spool/postfix/plesk/sdd_transport_maps
virtual_transport = plesk_virtual
plesk_virtual_destination_recipient_limit = 1
mailman_destination_recipient_limit = 1
mailbox_size_limit = 0
virtual_mailbox_limit = 0

Также встречается вариант: Recipient address rejected: User unknown in relay recipient table.

Причины проблемы и их решение:

Такого адресата не существует

Проверьте, корректно ли вы прописываете имя получателя письма.

Почтовый ящик еще не активировался

Вы только что создали почтовый ящик и пытаетесь отправить письмо на него. В этом случае подождите 10-15 минут и повторите попытку.

Нарушена маршрутизация почты

Возможно вы пользуетесь сторонним почтовым сервисом (Yandex почтой, Mail.ru, GoogleApps) в то время, как в настройках панели управления включена локальная почтовая служба. В этом случае проблему решит отключение локальной маршрутизации почты. Делается это в панели управления хостингом:

Готово! Вы отключили локальную почту.