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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 12:06:34 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 12:06:34 +0000
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tree2b467823aaeebc7ef8bc9e3cabe8074eaef1666d /README_FILES/STANDARD_CONFIGURATION_README
parentInitial commit. (diff)
downloadpostfix-upstream.tar.xz
postfix-upstream.zip
Adding upstream version 3.5.24.upstream/3.5.24upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+PPoossttffiixx SSttaannddaarrdd CCoonnffiigguurraattiioonn EExxaammpplleess
+
+-------------------------------------------------------------------------------
+
+PPuurrppoossee ooff tthhiiss ddooccuummeenntt
+
+This document presents a number of typical Postfix configurations. This
+document should be reviewed after you have followed the basic configuration
+steps as described in the BASIC_CONFIGURATION_README document. In particular,
+do not proceed here if you don't already have Postfix working for local mail
+submission and for local mail delivery.
+
+The first part of this document presents standard configurations that each
+solve one specific problem.
+
+ * Postfix on a stand-alone Internet host
+ * Postfix on a null client
+ * Postfix on a local network
+ * Postfix email firewall/gateway
+
+The second part of this document presents additional configurations for hosts
+in specific environments.
+
+ * Delivering some but not all accounts locally
+ * Running Postfix behind a firewall
+ * Configuring Postfix as primary or backup MX host for a remote site
+ * Postfix on a dialup machine
+ * Postfix on hosts without a real Internet hostname
+
+PPoossttffiixx oonn aa ssttaanndd--aalloonnee IInntteerrnneett hhoosstt
+
+Postfix should work out of the box without change on a stand-alone machine that
+has direct Internet access. At least, that is how Postfix installs when you
+download the Postfix source code via http://www.postfix.org/.
+
+You can use the command "ppoossttccoonnff --nn" to find out what settings are overruled
+by your main.cf. Besides a few pathname settings, few parameters should be set
+on a stand-alone box, beyond what is covered in the BASIC_CONFIGURATION_README
+document:
+
+ /etc/postfix/main.cf:
+ # Optional: send mail as user@domainname instead of user@hostname.
+ #myorigin = $mydomain
+
+ # Optional: specify NAT/proxy external address.
+ #proxy_interfaces = 1.2.3.4
+
+ # Alternative 1: don't relay mail from other hosts.
+ mynetworks_style = host
+ relay_domains =
+
+ # Alternative 2: relay mail from local clients only.
+ # mynetworks = 192.168.1.0/28
+ # relay_domains =
+
+See also the section "Postfix on hosts without a real Internet hostname" if
+this is applicable to your configuration.
+
+PPoossttffiixx oonn aa nnuullll cclliieenntt
+
+A null client is a machine that can only send mail. It receives no mail from
+the network, and it does not deliver any mail locally. A null client typically
+uses POP, IMAP or NFS for mailbox access.
+
+In this example we assume that the Internet domain name is "example.com" and
+that the machine is named "hostname.example.com". As usual, the examples show
+only parameters that are not left at their default settings.
+
+ 1 /etc/postfix/main.cf:
+ 2 myhostname = hostname.example.com
+ 3 myorigin = $mydomain
+ 4 relayhost = $mydomain
+ 5 inet_interfaces = loopback-only
+ 6 mydestination =
+
+Translation:
+
+ * Line 2: Set myhostname to hostname.example.com, in case the machine name
+ isn't set to a fully-qualified domain name (use the command "postconf -
+ d myhostname" to find out what the machine name is).
+
+ * Line 2: The myhostname value also provides the default value for the
+ mydomain parameter (here, "mydomain = example.com").
+
+ * Line 3: Send mail as "user@example.com" (instead of
+ "user@hostname.example.com"), so that nothing ever has a reason to send
+ mail to "user@hostname.example.com".
+
+ * Line 4: Forward all mail to the mail server that is responsible for the
+ "example.com" domain. This prevents mail from getting stuck on the null
+ client if it is turned off while some remote destination is unreachable.
+ Specify a real hostname here if your "example.com" domain has no MX record.
+
+ * Line 5: Do not accept mail from the network.
+
+ * Line 6: Disable local mail delivery. All mail goes to the mail server as
+ specified in line 4.
+
+PPoossttffiixx oonn aa llooccaall nneettwwoorrkk
+
+This section describes a local area network environment of one main server and
+multiple other systems that send and receive email. As usual we assume that the
+Internet domain name is "example.com". All systems are configured to send mail
+as "user@example.com", and all systems receive mail for
+"user@hostname.example.com". The main server also receives mail for
+"user@example.com". We call this machine by the name of mailhost.example.com.
+
+A drawback of sending mail as "user@example.com" is that mail for "root" and
+other system accounts is also sent to the central mailhost. See the section
+"Delivering some but not all accounts locally" below for possible solutions.
+
+As usual, the examples show only parameters that are not left at their default
+settings.
+
+First we present the non-mailhost configuration, because it is the simpler one.
+This machine sends mail as "user@example.com" and is final destination for
+"user@hostname.example.com".
+
+ 1 /etc/postfix/main.cf:
+ 2 myorigin = $mydomain
+ 3 mynetworks = 127.0.0.0/8 10.0.0.0/24
+ 4 relay_domains =
+ 5 # Optional: forward all non-local mail to mailhost
+ 6 #relayhost = $mydomain
+
+Translation:
+
+ * Line 2: Send mail as "user@example.com".
+
+ * Line 3: Specify the trusted networks.
+
+ * Line 4: This host does not relay mail from untrusted networks.
+
+ * Line 6: This is needed if no direct Internet access is available. See also
+ below, "Postfix behind a firewall".
+
+Next we present the mailhost configuration. This machine sends mail as
+"user@example.com" and is final destination for "user@hostname.example.com" as
+well as "user@example.com".
+
+ 1 DNS:
+ 2 example.com IN MX 10 mailhost.example.com.
+ 3
+ 4 /etc/postfix/main.cf:
+ 5 myorigin = $mydomain
+ 6 mydestination = $myhostname localhost.$mydomain localhost $mydomain
+ 7 mynetworks = 127.0.0.0/8 10.0.0.0/24
+ 8 relay_domains =
+ 9 # Optional: forward all non-local mail to firewall
+ 10 #relayhost = [firewall.example.com]
+
+Translation:
+
+ * Line 2: Send mail for the domain "example.com" to the machine
+ mailhost.example.com. Remember to specify the "." at the end of the line.
+
+ * Line 5: Send mail as "user@example.com".
+
+ * Line 6: This host is the final mail destination for the "example.com"
+ domain, in addition to the names of the machine itself.
+
+ * Line 7: Specify the trusted networks.
+
+ * Line 8: This host does not relay mail from untrusted networks.
+
+ * Line 10: This is needed only when the mailhost has to forward non-local
+ mail via a mail server on a firewall. The [] forces Postfix to do no MX
+ record lookups.
+
+In an environment like this, users access their mailbox in one or more of the
+following ways:
+
+ * Mailbox access via NFS or equivalent.
+
+ * Mailbox access via POP or IMAP.
+
+ * Mailbox on the user's preferred machine.
+
+In the latter case, each user has an alias on the mailhost that forwards mail
+to her preferred machine:
+
+ /etc/aliases:
+ joe: joe@joes.preferred.machine
+ jane: jane@janes.preferred.machine
+
+On some systems the alias database is not in /etc/aliases. To find out the
+location for your system, execute the command "ppoossttccoonnff aalliiaass__mmaappss".
+
+Execute the command "nneewwaalliiaasseess" whenever you change the aliases file.
+
+PPoossttffiixx eemmaaiill ffiirreewwaallll//ggaatteewwaayy
+
+The idea is to set up a Postfix email firewall/gateway that forwards mail for
+"example.com" to an inside gateway machine but rejects mail for
+"anything.example.com". There is only one problem: with "relay_domains =
+example.com", the firewall normally also accepts mail for
+"anything.example.com". That would not be right.
+
+Note: this example requires Postfix version 2.0 and later. To find out what
+Postfix version you have, execute the command "ppoossttccoonnff mmaaiill__vveerrssiioonn".
+
+The solution is presented in multiple parts. This first part gets rid of local
+mail delivery on the firewall, making the firewall harder to break.
+
+ 1 /etc/postfix/main.cf:
+ 2 myorigin = example.com
+ 3 mydestination =
+ 4 local_recipient_maps =
+ 5 local_transport = error:local mail delivery is disabled
+ 6
+ 7 /etc/postfix/master.cf:
+ 8 Comment out the local delivery agent
+
+Translation:
+
+ * Line 2: Send mail from this machine as "user@example.com", so that no
+ reason exists to send mail to "user@firewall.example.com".
+
+ * Lines 3-8: Disable local mail delivery on the firewall machine.
+
+For the sake of technical correctness the firewall must be able to receive mail
+for postmaster@[firewall ip address]. Reportedly, some things actually expect
+this ability to exist. The second part of the solution therefore adds support
+for postmaster@[firewall ip address], and as a bonus we do abuse@[firewall ip
+address] as well. All the mail to these two accounts is forwarded to an inside
+address.
+
+ 1 /etc/postfix/main.cf:
+ 2 virtual_alias_maps = hash:/etc/postfix/virtual
+ 3
+ 4 /etc/postfix/virtual:
+ 5 postmaster postmaster@example.com
+ 6 abuse abuse@example.com
+
+Translation:
+
+ * Because mydestination is empty (see the previous example), only address
+ literals matching $inet_interfaces or $proxy_interfaces are deemed local.
+ So "localpart@[a.d.d.r]" can be matched as simply "localpart" in canonical
+ (5) and virtual(5). This avoids the need to specify firewall IP addresses
+ into Postfix configuration files.
+
+The last part of the solution does the email forwarding, which is the real
+purpose of the firewall email function.
+
+ 1 /etc/postfix/main.cf:
+ 2 mynetworks = 127.0.0.0/8 12.34.56.0/24
+ 3 relay_domains = example.com
+ 4 parent_domain_matches_subdomains =
+ 5 debug_peer_list smtpd_access_maps
+
+ 6a # Postfix 2.10 and later support separate relay control and
+ 7a # spam control.
+ 8a smtpd_relay_restrictions =
+ 9a permit_mynetworks reject_unauth_destination
+ 10a smtpd_recipient_restrictions = ...spam blocking rules....
+
+ 6b # Older configurations combine relay control and spam control. To
+ 7b # use this with Postfix >= 2.10 specify "smtpd_relay_restrictions=".
+ 8b smtpd_recipient_restrictions =
+ 9b permit_mynetworks reject_unauth_destination
+ 10b ...spam blocking rules....
+
+ 11 relay_recipient_maps = hash:/etc/postfix/relay_recipients
+ 12 transport_maps = hash:/etc/postfix/transport
+ 13
+ 14 /etc/postfix/relay_recipients:
+ 15 user1@example.com x
+ 16 user2@example.com x
+ 17 . . .
+ 18
+ 19 /etc/postfix/transport:
+ 20 example.com smtp:[inside-gateway.example.com]
+
+Translation:
+
+ * Lines 1-10: Accept mail from local systems in $mynetworks, and accept mail
+ from outside for "user@example.com" but not for
+ "user@anything.example.com". The magic is in lines 4-5.
+
+ * Lines 11, 13-16: Define the list of valid addresses in the "example.com"
+ domain that can receive mail from the Internet. This prevents the mail
+ queue from filling up with undeliverable MAILER-DAEMON messages. If you
+ can't maintain a list of valid recipients then you must specify
+ "relay_recipient_maps =" (that is, an empty value), or you must specify an
+ "@example.com x" wild-card in the relay_recipients table.
+
+ * Lines 12, 19-20: Route mail for "example.com" to the inside gateway
+ machine. The [] forces Postfix to do no MX lookup.
+
+Specify ddbbmm instead of hhaasshh if your system uses ddbbmm files instead of ddbb files.
+To find out what lookup tables Postfix supports, use the command "ppoossttccoonnff --mm".
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//rreellaayy__rreecciippiieennttss" whenever you change
+the relay_recipients table.
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//ttrraannssppoorrtt" whenever you change the
+transport table.
+
+In some installations, there may be separate instances of Postfix processing
+inbound and outbound mail on a multi-homed firewall. The inbound Postfix
+instance has an SMTP server listening on the external firewall interface, and
+the outbound Postfix instance has an SMTP server listening on the internal
+interface. In such a configuration is it is tempting to configure
+$inet_interfaces in each instance with just the corresponding interface
+address.
+
+In most cases, using inet_interfaces in this way will not work, because as
+documented in the $inet_interfaces reference manual, the smtp(8) delivery agent
+will also use the specified interface address as the source address for
+outbound connections and will be unable to reach hosts on "the other side" of
+the firewall. The symptoms are that the firewall is unable to connect to hosts
+that are in fact up. See the inet_interfaces parameter documentation for
+suggested work-arounds.
+
+DDeelliivveerriinngg ssoommee bbuutt nnoott aallll aaccccoouunnttss llooccaallllyy
+
+A drawback of sending mail as "user@example.com" (instead of
+"user@hostname.example.com") is that mail for "root" and other system accounts
+is also sent to the central mailhost. In order to deliver such accounts
+locally, you can set up virtual aliases as follows:
+
+ 1 /etc/postfix/main.cf:
+ 2 virtual_alias_maps = hash:/etc/postfix/virtual
+ 3
+ 4 /etc/postfix/virtual:
+ 5 root root@localhost
+ 6 . . .
+
+Translation:
+
+ * Line 5: As described in the virtual(5) manual page, the bare name "root"
+ matches "root@site" when "site" is equal to $myorigin, when "site" is
+ listed in $mydestination, or when it matches $inet_interfaces or
+ $proxy_interfaces.
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//vviirrttuuaall" after editing the file.
+
+RRuunnnniinngg PPoossttffiixx bbeehhiinndd aa ffiirreewwaallll
+
+The simplest way to set up Postfix on a host behind a firewalled network is to
+send all mail to a gateway host, and to let that mail host take care of
+internal and external forwarding. Examples of that are shown in the local area
+network section above. A more sophisticated approach is to send only external
+mail to the gateway host, and to send intranet mail directly.
+
+Note: this example requires Postfix version 2.0 and later. To find out what
+Postfix version you have, execute the command "ppoossttccoonnff mmaaiill__vveerrssiioonn".
+
+The following example presents additional configuration. You need to combine
+this with basic configuration information as discussed the first half of this
+document.
+
+ 1 /etc/postfix/main.cf:
+ 2 transport_maps = hash:/etc/postfix/transport
+ 3 relayhost =
+ 4 # Optional for a machine that isn't "always on"
+ 5 #fallback_relay = [gateway.example.com]
+ 6
+ 7 /etc/postfix/transport:
+ 8 # Internal delivery.
+ 9 example.com :
+ 10 .example.com :
+ 11 # External delivery.
+ 12 * smtp:[gateway.example.com]
+
+Translation:
+
+ * Lines 2, 7-12: Request that intranet mail is delivered directly, and that
+ external mail is given to a gateway. Obviously, this example assumes that
+ the organization uses DNS MX records internally. The [] forces Postfix to
+ do no MX lookup.
+
+ * Line 3: IMPORTANT: do not specify a relayhost in main.cf.
+
+ * Line 5: This prevents mail from being stuck in the queue when the machine
+ is turned off. Postfix tries to deliver mail directly, and gives
+ undeliverable mail to a gateway.
+
+Specify ddbbmm instead of hhaasshh if your system uses ddbbmm files instead of ddbb files.
+To find out what lookup tables Postfix supports, use the command "ppoossttccoonnff --mm".
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//ttrraannssppoorrtt" whenever you edit the
+transport table.
+
+CCoonnffiigguurriinngg PPoossttffiixx aass pprriimmaarryy oorr bbaacckkuupp MMXX hhoosstt ffoorr aa rreemmoottee ssiittee
+
+This section presents additional configuration. You need to combine this with
+basic configuration information as discussed the first half of this document.
+
+When your system is SECONDARY MX host for a remote site this is all you need:
+
+ 1 DNS:
+ 2 the.backed-up.domain.tld IN MX 100 your.machine.tld.
+ 3
+ 4 /etc/postfix/main.cf:
+ 5 relay_domains = . . . the.backed-up.domain.tld
+
+ 6a # Postfix 2.10 and later support separate relay control and
+ 7a # spam control.
+ 8a smtpd_relay_restrictions =
+ 9a permit_mynetworks reject_unauth_destination
+ 10a smtpd_recipient_restrictions = ...spam blocking rules....
+
+ 6b # Older configurations combine relay control and spam control. To
+ 7b # use this with Postfix >= 2.10 specify "smtpd_relay_restrictions=".
+ 8b smtpd_recipient_restrictions =
+ 9b permit_mynetworks reject_unauth_destination
+ 10b ...spam blocking rules....
+
+ 11 # You must specify your NAT/proxy external address.
+ 12 #proxy_interfaces = 1.2.3.4
+ 13
+ 14 relay_recipient_maps = hash:/etc/postfix/relay_recipients
+ 15
+ 16 /etc/postfix/relay_recipients:
+ 17 user1@the.backed-up.domain.tld x
+ 18 user2@the.backed-up.domain.tld x
+ 19 . . .
+
+When your system is PRIMARY MX host for a remote site you need the above, plus:
+
+ 20 /etc/postfix/main.cf:
+ 21 transport_maps = hash:/etc/postfix/transport
+ 22
+ 23 /etc/postfix/transport:
+ 24 the.backed-up.domain.tld relay:[their.mail.host.tld]
+
+Important notes:
+
+ * Do not list the.backed-up.domain.tld in mydestination.
+
+ * Do not list the.backed-up.domain.tld in virtual_alias_domains.
+
+ * Do not list the.backed-up.domain.tld in virtual_mailbox_domains.
+
+ * Lines 1-9: Forward mail from the Internet for "the.backed-up.domain.tld" to
+ the primary MX host for that domain.
+
+ * Line 12: This is a must if Postfix receives mail via a NAT relay or proxy
+ that presents a different IP address to the world than the local machine.
+
+ * Lines 14-18: Define the list of valid addresses in the "the.backed-
+ up.domain.tld" domain. This prevents your mail queue from filling up with
+ undeliverable MAILER-DAEMON messages. If you can't maintain a list of valid
+ recipients then you must specify "relay_recipient_maps =" (that is, an
+ empty value), or you must specify an "@the.backed-up.domain.tld x" wild-
+ card in the relay_recipients table.
+
+ * Line 24: The [] forces Postfix to do no MX lookup.
+
+Specify ddbbmm instead of hhaasshh if your system uses ddbbmm files instead of ddbb files.
+To find out what lookup tables Postfix supports, use the command "ppoossttccoonnff --mm".
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//ttrraannssppoorrtt" whenever you change the
+transport table.
+
+NOTE for Postfix < 2.2: Do not use the fallback_relay feature when relaying
+mail for a backup or primary MX domain. Mail would loop between the Postfix MX
+host and the fallback_relay host when the final destination is unavailable.
+
+ * In main.cf specify "relay_transport = relay",
+ * In master.cf specify "-o fallback_relay =" at the end of the relay entry.
+ * In transport maps, specify "relay:nexthop..." as the right-hand side for
+ backup or primary MX domain entries.
+
+These are default settings in Postfix version 2.2 and later.
+
+PPoossttffiixx oonn aa ddiiaalluupp mmaacchhiinnee
+
+This section applies to dialup connections that are down most of the time. For
+dialup connections that are up 24x7, see the local area network section above.
+
+This section presents additional configuration. You need to combine this with
+basic configuration information as discussed the first half of this document.
+
+If you do not have your own hostname and IP address (usually with dialup, cable
+TV or DSL connections) then you should also study the section on "Postfix on
+hosts without a real Internet hostname".
+
+ * Route all outgoing mail to your network provider.
+ If your machine is disconnected most of the time, there isn't a lot of
+ opportunity for Postfix to deliver mail to hard-to-reach corners of the
+ Internet. It's better to give the mail to a machine that is connected all
+ the time. In the example below, the [] prevents Postfix from trying to look
+ up DNS MX records.
+
+ /etc/postfix/main.cf:
+ relayhost = [smtprelay.someprovider.com]
+
+ * Disable spontaneous SMTP mail delivery (if using on-demand dialup IP only).
+
+ Normally, Postfix attempts to deliver outbound mail at its convenience. If
+ your machine uses on-demand dialup IP, this causes your system to place a
+ telephone call whenever you submit new mail, and whenever Postfix retries
+ to deliver delayed mail. To prevent such telephone calls from being placed,
+ disable spontaneous SMTP mail deliveries.
+
+ /etc/postfix/main.cf:
+ defer_transports = smtp (Only for on-demand dialup IP hosts)
+
+ * Disable SMTP client DNS lookups (dialup LAN only).
+
+ /etc/postfix/main.cf:
+ disable_dns_lookups = yes (Only for on-demand dialup IP hosts)
+
+ * Flush the mail queue whenever the Internet link is established.
+ Put the following command into your PPP or SLIP dialup scripts:
+
+ /usr/sbin/sendmail -q (whenever the Internet link is up)
+
+ The exact location of the Postfix sendmail command is system-specific. Use
+ the command "ppoossttccoonnff sseennddmmaaiill__ppaatthh" to find out where the Postfix sendmail
+ command is located on your machine.
+
+ In order to find out if the mail queue is flushed, use something like:
+
+ #!/bin/sh
+
+ # Start mail deliveries.
+ /usr/sbin/sendmail -q
+
+ # Allow deliveries to start.
+ sleep 10
+
+ # Loop until all messages have been tried at least once.
+ while mailq | grep '^[^ ]*\*' >/dev/null
+ do
+ sleep 10
+ done
+
+ If you have disabled spontaneous SMTP mail delivery, you also need to run
+ the "sseennddmmaaiill --qq" command every now and then while the dialup link is up,
+ so that newly-posted mail is flushed from the queue.
+
+PPoossttffiixx oonn hhoossttss wwiitthhoouutt aa rreeaall IInntteerrnneett hhoossttnnaammee
+
+This section is for hosts that don't have their own Internet hostname.
+Typically these are systems that get a dynamic IP address via DHCP or via
+dialup. Postfix will let you send and receive mail just fine between accounts
+on a machine with a fantasy name. However, you cannot use a fantasy hostname in
+your email address when sending mail into the Internet, because no-one would be
+able to reply to your mail. In fact, more and more sites refuse mail addresses
+with non-existent domain names.
+
+Note: the following information is Postfix version dependent. To find out what
+Postfix version you have, execute the command "ppoossttccoonnff mmaaiill__vveerrssiioonn".
+
+SSoolluuttiioonn 11:: PPoossttffiixx vveerrssiioonn 22..22 aanndd llaatteerr
+
+Postfix 2.2 uses the generic(5) address mapping to replace local fantasy email
+addresses by valid Internet addresses. This mapping happens ONLY when mail
+leaves the machine; not when you send mail between users on the same machine.
+
+The following example presents additional configuration. You need to combine
+this with basic configuration information as discussed the first half of this
+document.
+
+ 1 /etc/postfix/main.cf:
+ 2 smtp_generic_maps = hash:/etc/postfix/generic
+ 3
+ 4 /etc/postfix/generic:
+ 5 his@localdomain.local hisaccount@hisisp.example
+ 6 her@localdomain.local heraccount@herisp.example
+ 7 @localdomain.local hisaccount+local@hisisp.example
+
+When mail is sent to a remote host via SMTP:
+
+ * Line 5 replaces his@localdomain.local by his ISP mail address,
+
+ * Line 6 replaces her@localdomain.local by her ISP mail address, and
+
+ * Line 7 replaces other local addresses by his ISP account, with an address
+ extension of +local (this example assumes that the ISP supports "+" style
+ address extensions).
+
+Specify ddbbmm instead of hhaasshh if your system uses ddbbmm files instead of ddbb files.
+To find out what lookup tables Postfix supports, use the command "ppoossttccoonnff --mm".
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//ggeenneerriicc" whenever you change the
+generic table.
+
+SSoolluuttiioonn 22:: PPoossttffiixx vveerrssiioonn 22..11 aanndd eeaarrlliieerr
+
+The solution with older Postfix systems is to use valid Internet addresses
+where possible, and to let Postfix map valid Internet addresses to local
+fantasy addresses. With this, you can send mail to the Internet and to local
+fantasy addresses, including mail to local fantasy addresses that don't have a
+valid Internet address of their own.
+
+The following example presents additional configuration. You need to combine
+this with basic configuration information as discussed the first half of this
+document.
+
+ 1 /etc/postfix/main.cf:
+ 2 myhostname = hostname.localdomain
+ 3 mydomain = localdomain
+ 4
+ 5 canonical_maps = hash:/etc/postfix/canonical
+ 6
+ 7 virtual_alias_maps = hash:/etc/postfix/virtual
+ 8
+ 9 /etc/postfix/canonical:
+ 10 your-login-name your-account@your-isp.com
+ 11
+ 12 /etc/postfix/virtual:
+ 13 your-account@your-isp.com your-login-name
+
+Translation:
+
+ * Lines 2-3: Substitute your fantasy hostname here. Do not use a domain name
+ that is already in use by real organizations on the Internet. See RFC 2606
+ for examples of domain names that are guaranteed not to be owned by anyone.
+
+ * Lines 5, 9, 10: This provides the mapping from "your-login-
+ name@hostname.localdomain" to "your-account@your-isp.com". This part is
+ required.
+
+ * Lines 7, 12, 13: Deliver mail for "your-account@your-isp.com" locally,
+ instead of sending it to the ISP. This part is not required but is
+ convenient.
+
+Specify ddbbmm instead of hhaasshh if your system uses ddbbmm files instead of ddbb files.
+To find out what lookup tables Postfix supports, use the command "ppoossttccoonnff --mm".
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//ccaannoonniiccaall" whenever you change the
+canonical table.
+
+Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//vviirrttuuaall" whenever you change the
+virtual table.
+