From 5e61585d76ae77fd5e9e96ebabb57afa4d74880d Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 14:06:34 +0200 Subject: Adding upstream version 3.5.24. Signed-off-by: Daniel Baumann --- html/ADDRESS_REWRITING_README.html | 1246 ++++++++++++++++++++++++++++++++++++ 1 file changed, 1246 insertions(+) create mode 100644 html/ADDRESS_REWRITING_README.html (limited to 'html/ADDRESS_REWRITING_README.html') diff --git a/html/ADDRESS_REWRITING_README.html b/html/ADDRESS_REWRITING_README.html new file mode 100644 index 0000000..3c76edb --- /dev/null +++ b/html/ADDRESS_REWRITING_README.html @@ -0,0 +1,1246 @@ + + + + + + +Postfix Address Rewriting + + + + + + + +

Postfix +Address Rewriting

+ +
+ +

Postfix address rewriting purpose

+ +

Address rewriting is at the heart of the Postfix mail system. +Postfix rewrites addresses for many different purposes. Some are +merely cosmetic, and some are necessary to deliver correctly +formatted mail to the correct destination. Examples of +address rewriting in Postfix are:

+ + + +

Although Postfix currently has no address rewriting language, +it can do surprisingly powerful address manipulation via table +lookup. Postfix typically uses lookup tables with fixed strings +to map one address to one or multiple addresses, and typically uses +regular expressions to map multiple addresses to one or multiple +addresses. Fixed-string lookup tables may be in the form of local +files, or in the form of NIS, LDAP or SQL databases. The +DATABASE_README document gives an introduction to Postfix lookup +tables.

+ +

Topics covered in this document:

+ + + +

To rewrite message headers or not, or to label +as invalid

+ +

Postfix versions 2.1 and earlier always rewrite message header +addresses, and append Postfix's own domain information to addresses +that Postfix considers incomplete. While rewriting message header +addresses is OK for mail with a local origin, it is undesirable +for remote mail:

+ + + +

Postfix versions 2.2 give you the option to either not rewrite +message headers from remote SMTP clients at all, or to label +incomplete addresses in such message headers as invalid. Here is +how it works:

+ + + +

Postfix address rewriting overview

+ +

The figure below zooms in on those parts of Postfix that are most +involved with address rewriting activity. See the OVERVIEW document +for an overview of the complete Postfix architecture. Names followed +by a number are Postfix daemon programs, while unnumbered names +represent Postfix queues or internal sources of mail messages.

+ +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
trivial-
rewrite(8)
(std +form) 		trivial-
rewrite(8)
(resolve) +
^
| + 		|
v
+ +
^
| + 		|
v
+ +
smtpd(8) + >- + cleanup(8) -> + incoming -> + active -> + qmgr(8) -< + +smtp(8)
+qmqpd(8) lmtp(8)
pickup(8) + local(8) +
^
|
^
| + 		|
v
+ +
bounces
forwarding
notices		 deferred + +
+ +
+ +

The table below summarizes all Postfix address manipulations. +If you're reading this document for the first time, skip forward +to "Address +rewriting when mail is received". Once you've finished reading +the remainder of this document, the table will help you to quickly +find what you need.

+ +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Address manipulation Scope Daemon Global turn-on control Selective +turn-off control
Rewrite addresses to standard form + all mail trivial-
rewrite(8) 		append_at_myorigin, append_dot_mydomain, swap_bangpath, +allow_percent_hack local_header_rewrite_clients, +remote_header_rewrite_domain
Canonical address mapping all mail cleanup(8) canonical_maps + receive_override_options, local_header_rewrite_clients, +remote_header_rewrite_domain
Address masquerading all mail cleanup(8) masquerade_domains + receive_override_options, local_header_rewrite_clients, +remote_header_rewrite_domain
Automatic BCC recipients new mail cleanup(8) always_bcc, +sender_bcc_maps, recipient_bcc_maps receive_override_options +
Virtual aliasing all mail cleanup(8) virtual_alias_maps + receive_override_options
Resolve address to destination + all mail trivial-
rewrite(8) 		none none
Mail transport switch all mail trivial-
rewrite(8) 		+transport_maps none
Relocated users table all mail trivial-
rewrite(8) 		+relocated_maps none
Generic mapping table +outgoing SMTP mail smtp(8) smtp_generic_maps + none
Local alias database +local mail only local(8) alias_maps none +
Local per-user .forward files + local mail only local(8) forward_path + none
Local catch-all address local mail only local(8) luser_relay +none
+ +
+ +

Address rewriting when mail is received +

+ +

The cleanup(8) server receives mail from outside of Postfix as +well as mail from internal sources such as forwarded mail, +undeliverable mail that is bounced to the sender, and postmaster +notifications about problems with the mail system.

+ +

The cleanup(8) server transforms the sender, recipients and +message content into a standard form before writing it to an incoming +queue file. The server cleans up sender and recipient addresses in +message headers and in the envelope, adds missing message headers +such as From: or Date: that are required by mail standards, and +removes message headers such as Bcc: that should not be present. +The cleanup(8) server delegates the more complex address manipulations +to the trivial-rewrite(8) server as described later in this document. +

+ +

Address manipulations at this stage are:

+ + + +

Rewrite addresses to standard form

+ +

Before the cleanup(8) daemon runs an address through any address +mapping lookup table, it first rewrites the address to the standard +"user@fully.qualified.domain" form, by sending the address to the +trivial-rewrite(8) daemon. The purpose of rewriting to standard +form is to reduce the number of entries needed in lookup tables. +

+ +

The Postfix trivial-rewrite(8) daemon implements the following +hard-coded address manipulations:

+ +
+ +
+ +
Rewrite "@hosta,@hostb:user@site" to "user@site"
+ +

In case you wonder what this is, the address form above +is called a route address, and specifies that mail for "user@site" +be delivered via "hosta" and "hostb". Usage of this form has been +deprecated for a long time. Postfix has no ability to handle route +addresses, other than to strip off the route part.

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter, or if the +remote_header_rewrite_domain configuration parameter specifies a +non-empty value. To get the behavior before Postfix 2.2, specify +"local_header_rewrite_clients = static:all".

+ +
Rewrite "site!user" to "user@site"
+ +

This feature is controlled by the boolean swap_bangpath +parameter (default: yes). The purpose is to rewrite UUCP-style +addresses to domain style. This is useful only when you receive +mail via UUCP, but it probably does not hurt otherwise.

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter, or if the +remote_header_rewrite_domain configuration parameter specifies a +non-empty value. To get the behavior before Postfix 2.2, specify +"local_header_rewrite_clients = static:all".

+ +
Rewrite "user%domain" to "user@domain"
+ +

This feature is controlled by the boolean allow_percent_hack +parameter (default: yes). Typically, this is used in order to deal +with monstrosities such as "user%domain@otherdomain".

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter, or if the +remote_header_rewrite_domain configuration parameter specifies a +non-empty value. To get the behavior before Postfix 2.2, specify +"local_header_rewrite_clients = static:all".

+ +
+ +Rewrite "user" to "user@$myorigin"
+ +

This feature is controlled by the boolean append_at_myorigin +parameter (default: yes). You should never turn off this feature, +because a lot of Postfix components expect that all addresses have +the form "user@domain".

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter; otherwise they append the +domain name specified with the remote_header_rewrite_domain +configuration parameter, if one is specified. To get the behavior +before Postfix 2.2, specify "local_header_rewrite_clients = +static:all".

+ +

If your machine is not the main machine for $myorigin and you +wish to have some users delivered locally without going via that +main machine, make an entry in the virtual +alias table that redirects "user@$myorigin" to +"user@$myhostname". See also the "delivering some +users locally" section in the STANDARD_CONFIGURATION_README +document.

+ +
+ +Rewrite "user@host" to "user@host.$mydomain"
+ +

This feature is controlled by the boolean append_dot_mydomain +parameter (default: yes). The purpose is to get consistent treatment +of different forms of the same hostname.

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter; otherwise they append the +domain name specified with the remote_header_rewrite_domain +configuration parameter, if one is specified. To get the behavior +before Postfix 2.2, specify "local_header_rewrite_clients = +static:all".

+ +

Some will argue that rewriting "host" to "host.domain" +is bad. That is why it can be turned off. Others like the convenience +of having Postfix's own domain appended automatically.

+ +
Rewrite "user@site." to "user@site" (without the trailing dot).
+ +

A single trailing dot is silently removed. However, an +address that ends in multiple dots will be rejected as an invalid +address.

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter, or if the +remote_header_rewrite_domain configuration parameter specifies a +non-empty value. To get the behavior before Postfix 2.2, specify +"local_header_rewrite_clients = static:all".

+ +
+ +
+ +

Canonical address mapping

+ +

The cleanup(8) daemon uses the canonical(5) tables to rewrite +addresses in message envelopes and in message headers. By default +all header and envelope addresses are rewritten; this is controlled +with the canonical_classes configuration parameter.

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter, or if the +remote_header_rewrite_domain configuration parameter specifies a +non-empty value. To get the behavior before Postfix 2.2, specify +"local_header_rewrite_clients = static:all".

+ +

Address rewriting is +done for local and remote addresses. The mapping is useful to +replace login names by "Firstname.Lastname" style addresses, or to +clean up invalid domains in mail addresses produced by legacy mail +systems.

+ +

Canonical mapping is disabled by default. To enable, edit the +canonical_maps parameter in the main.cf file and specify one or +more lookup tables, separated by whitespace or commas.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    canonical_maps = hash:/etc/postfix/canonical
+
+/etc/postfix/canonical:
+    wietse        Wietse.Venema
+
+
+ +

For static mappings as shown above, lookup tables such as hash:, +ldap:, mysql: or pgsql: are sufficient. For dynamic mappings you +can use regular expression tables. This requires that you become +intimately familiar with the ideas expressed in regexp_table(5), +pcre_table(5) and canonical(5).

+ +

In addition to the canonical maps which are applied to both sender +and recipient addresses, you can specify canonical maps that are +applied only to sender addresses or to recipient addresses.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    sender_canonical_maps = hash:/etc/postfix/sender_canonical
+    recipient_canonical_maps = hash:/etc/postfix/recipient_canonical
+
+
+ +

The sender and recipient canonical maps are applied before the +common canonical maps. The sender_canonical_classes and +recipient_canonical_classes parameters control what addresses are +subject to sender_canonical_maps and recipient_canonical_maps +mappings, respectively.

+ +

Sender-specific rewriting is useful when you want to rewrite +ugly sender addresses to pretty ones, and still want to be able to +send mail to the those ugly address without creating a mailer loop. +

+ +

Canonical mapping can be turned off selectively for mail received +by smtpd(8), qmqpd(8), or pickup(8), by overriding main.cf settings +in the master.cf file. This feature is available in Postfix version +2.1 and later.

+ +

Example:

+ +
+
+/etc/postfix/master.cf:
+    127.0.0.1:10026    inet  n      -      n      -      -     smtpd
+        -o receive_override_options=no_address_mappings
+
+
+ +

Note: do not specify whitespace around the "=" here.

+ +

Address masquerading

+ +

Address masquerading is a method to hide hosts inside a domain +behind their mail gateway, and to make it appear as if the mail +comes from the gateway itself, instead of from individual machines. +

+ +

NOTE: Postfix versions 2.2 and later rewrite message headers +from remote SMTP clients only if the client matches the +local_header_rewrite_clients parameter, or if the +remote_header_rewrite_domain configuration parameter specifies a +non-empty value. To get the behavior before Postfix 2.2, specify +"local_header_rewrite_clients = static:all".

+ +

Address masquerading is disabled by default, and is implemented +by the cleanup(8) server. To enable, edit the masquerade_domains +parameter in the main.cf file and specify one or more domain names +separated by whitespace or commas. When Postfix tries to masquerade +a domain, it processes the list from left to right, and processing +stops at the first match.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    masquerade_domains = foo.example.com example.com
+
+
+ +

strips "any.thing.foo.example.com" to "foo.example.com", but +strips "any.thing.else.example.com" to "example.com".

+ +

A domain name prefixed with "!" means do not masquerade +this domain or its subdomains:

+ +
+
+/etc/postfix/main.cf:
+    masquerade_domains = !foo.example.com example.com
+
+
+ +

does not change "any.thing.foo.example.com" and "foo.example.com", +but strips "any.thing.else.example.com" to "example.com".

+ +

The masquerade_exceptions configuration parameter specifies +what user names should not be subjected to address masquerading. +Specify one or more user names separated by whitespace or commas. +

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    masquerade_exceptions = root
+
+
+ +

By default, Postfix makes no exceptions.

+ +

Subtle point: by default, address masquerading is applied only to +message headers and to envelope sender addresses, but not to envelope +recipients. This allows you to use address masquerading on a mail +gateway machine, while still being able to forward mail from outside +to users on individual machines.

+ +

In order to subject envelope recipient addresses to masquerading, +too, specify (Postfix version 1.1 and later):

+ +
+
+/etc/postfix/main.cf:
+    masquerade_classes = envelope_sender, envelope_recipient,
+        header_sender, header_recipient
+
+
+ +

If you rewrite the envelope recipient like this, Postfix will +no longer be able to send mail to individual machines.

+ +

Address masquerading can be turned off selectively for mail +received by smtpd(8), qmqpd(8), or pickup(8), by overriding main.cf +settings in the master.cf file. This feature is available in +Postfix version 2.1 and later.

+ +

Example:

+ +
+
+/etc/postfix/master.cf:
+    127.0.0.1:10026    inet  n      -      n      -      -     smtpd
+        -o receive_override_options=no_address_mappings
+
+
+ +

Note: do not specify whitespace around the "=" here.

+ +

Automatic BCC recipients

+ +

After applying the canonical and masquerade mappings, the +cleanup(8) daemon can generate optional BCC (blind carbon-copy) +recipients. Postfix provides three mechanisms:

+ +
+ +
+ +
always_bcc = address
Deliver a copy of all mail to +the specified address. In Postfix versions before 2.1, this feature +is implemented by smtpd(8), qmqpd(8), or pickup(8).
+ +
sender_bcc_maps = type:table
Search the specified +"type:table" lookup table with the envelope sender address for an +automatic BCC address. This feature is available in Postfix 2.1 +and later.
+ +
recipient_bcc_maps = type:table
Search the specified +"type:table" lookup table with the envelope recipient address for +an automatic BCC address. This feature is available in Postfix 2.1 +and later.
+ +
+ +
+ +

Note: automatic BCC recipients are produced only for new mail. +To avoid mailer loops, automatic BCC recipients are not generated +for mail that Postfix forwards internally, nor for mail that Postfix +generates itself.

+ +

Automatic BCC recipients (including always_bcc) can be turned +off selectively for mail received by smtpd(8), qmqpd(8), or pickup(8), +by overriding main.cf settings in the master.cf file. This feature +is available in Postfix version 2.1 and later.

+ +

Example:

+ +
+
+/etc/postfix/master.cf:
+    127.0.0.1:10026    inet  n      -      n      -      -     smtpd
+        -o receive_override_options=no_address_mappings
+
+
+ +

Note: do not specify whitespace around the "=" here.

+ +

Virtual aliasing

+ +

Before writing the recipients to the queue file, the cleanup(8) +daemon uses the optional virtual(5) alias tables to redirect mail +for recipients. The mapping affects only envelope recipient +addresses; it has no effect on message headers or envelope sender +addresses. Virtual alias lookups are useful to redirect mail for +virtual alias domains to real user mailboxes, and to redirect mail +for domains that no longer exist. Virtual alias lookups can also +be used to transform " Firstname.Lastname " back into UNIX login +names, although it seems that local aliases +may be a more appropriate vehicle. See the VIRTUAL_README document +for an overview of methods to host virtual domains with Postfix. +

+ +

Virtual aliasing is disabled by default. To enable, edit the +virtual_alias_maps parameter in the main.cf file and +specify one or more lookup tables, separated by whitespace or +commas.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    virtual_alias_maps = hash:/etc/postfix/virtual
+
+/etc/postfix/virtual:
+    Wietse.Venema        wietse
+
+
+ +

Addresses found in virtual alias maps are subjected to another +iteration of virtual aliasing, but are not subjected to canonical +mapping, in order to avoid loops.

+ +

For static mappings as shown above, lookup tables such as hash:, +ldap:, mysql: or pgsql: are sufficient. For dynamic mappings you +can use regular expression tables. This requires that you become +intimately familiar with the ideas expressed in regexp_table(5), +pcre_table(5) and virtual(5).

+ +

Virtual aliasing can be turned off selectively for mail received +by smtpd(8), qmqpd(8), or pickup(8), by overriding main.cf settings +in the master.cf file. This feature is available in Postfix version +2.1 and later.

+ +

Example:

+ +
+
+/etc/postfix/master.cf:
+    127.0.0.1:10026    inet  n      -      n      -      -     smtpd
+        -o receive_override_options=no_address_mappings
+
+
+ +

Note: do not specify whitespace around the "=" here.

+ +

At this point the message is ready to be stored into the +Postfix incoming queue.

+ +

Address rewriting when mail is delivered

+ +

The Postfix queue manager sorts mail according to its destination +and gives it to Postfix delivery agents such as local(8), smtp(8), +or lmtp(8). Just like the cleanup(8) server, the Postfix queue +manager delegates the more complex address manipulations to the +trivial-rewrite(8) server.

+ +

Address manipulations at this stage are:

+ + + +

Each Postfix delivery agent tries to deliver the mail to its +destination, while encapsulating the sender, recipients, and message +content according to the rules of the SMTP, LMTP, etc. protocol. +When mail cannot be delivered, it is either returned to the sender +or moved to the deferred queue and tried again later.

+ +

Address manipulations when mail is delivered +via the smtp(8) delivery agent:

+ + + +

Address manipulations when mail is delivered +via the local(8) delivery agent:

+ + + +

The remainder of this document presents each address manipulation +step in more detail, with specific examples or with pointers to +documentation with examples.

+ +

Resolve address to destination

+ +

The Postfix qmgr(8) queue manager selects new mail from the +incoming queue or old mail from the deferred queue, and asks the +trivial-rewrite(8) address rewriting and resolving daemon where it +should be delivered.

+ +

As of version 2.0, Postfix distinguishes four major address +classes. Each class has its own list of domain names, and each +class has its own default delivery method, as shown in the table +below. See the ADDRESS_CLASS_README document for the fine details. +Postfix versions before 2.0 only distinguish between local delivery +and everything else.

+ +
+ + + + + + + + + + + + + + + + +
Destination domain list Default delivery method Availability +
$mydestination, $inet_interfaces, $proxy_interfaces $local_transport Postfix 1.0
$virtual_mailbox_domains $virtual_transport Postfix 2.0
$relay_domains $relay_transport Postfix +2.0
none $default_transport Postfix 1.0
+ +
+ +

Mail transport switch

+ +

Once the trivial-rewrite(8) daemon has determined a default +delivery method it searches the optional transport(5) table for +information that overrides the message destination and/or delivery +method. Typical use of the transport(5) table is to send mail to +a system +that is not connected to the Internet, or to use a special SMTP +client configuration for destinations that have special requirements. +See, for example, the STANDARD_CONFIGURATION_README and UUCP_README +documents, and the examples in the transport(5) manual page.

+ +

Transport table lookups are disabled by default. To enable, +edit the transport_maps parameter in the main.cf file and specify +one or more lookup tables, separated by whitespace or commas.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    transport_maps = hash:/etc/postfix/transport
+
+
+ +

Relocated users table

+ +

Next, the trivial-rewrite(8) address rewriting and resolving +daemon runs each recipient through the relocated(5) database. This +table provides information on how to reach users that no longer +have an account, or what to do with mail for entire domains that +no longer exist. When mail is sent to an address that is listed +in this table, the message is returned to the sender with an +informative message.

+ +

The relocated(5) database is searched after transport(5) +table lookups, in anticipation of transport(5) tables that +can replace one recipient address by a different one.

+ +

Lookups of relocated users are disabled by default. To enable, +edit the relocated_maps parameter in the main.cf file and specify +one or more lookup tables, separated by whitespace or commas.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    relocated_maps = hash:/etc/postfix/relocated
+
+/etc/postfix/relocated:
+    username@example.com      otheruser@elsewhere.tld
+
+
+ +

As of Postfix version 2, mail for a relocated user will be +rejected by the SMTP server with the reason "user has moved to +otheruser@elsewhere.tld". Older Postfix versions will receive the +mail first, and then return it to the sender as undeliverable, with +the same reason.

+ +

Generic mapping for outgoing SMTP mail

+ +

Some hosts have no valid Internet domain name, and instead use +a name such as localdomain.local. This can be a problem when +you want to send mail over the Internet, because many mail servers +reject mail addresses with invalid domain names.

+ +

With the smtp_generic_maps parameter you can specify generic(5) +lookup tables that replace local mail addresses by valid Internet +addresses when mail leaves the machine via SMTP. The generic(5) +mapping replaces envelope and header addresses, and is non-recursive. +It does not happen when you send mail between addresses on the +local machine.

+ +

This feature is available in Postfix version 2.2 and later.

+ +

Example:

+ +
+
+/etc/postfix/main.cf:
+    smtp_generic_maps = hash:/etc/postfix/generic
+
+/etc/postfix/generic:
+    his@localdomain.local               hisaccount@hisisp.example
+    her@localdomain.local               heraccount@herisp.example
+    @localdomain.local                  hisaccount+local@hisisp.example
+
+
+ +

When mail is sent to a remote host via SMTP, this replaces +his@localdomain.local by his ISP mail address, replaces +her@localdomain.local by her ISP mail address, and replaces +other local addresses by his ISP account, with an address extension +of +local (this example assumes that the ISP supports "+" +style address extensions).

+ +

Local alias database

+ +

When mail is to be delivered locally, the local(8) delivery +agent runs each local recipient name through the aliases(5) database. +The mapping does not affect addresses in message headers. Local +aliases are typically used to implement distribution lists, or to +direct mail for standard aliases such as postmaster to real people. +The table can also be used to map "Firstname.Lastname" addresses +to login names.

+ +

Alias lookups are enabled by default. The default configuration +depends on the operating system environment, but it is typically +one of the following:

+ +
+
+/etc/postfix/main.cf:
+    alias_maps = hash:/etc/aliases
+    alias_maps = dbm:/etc/aliases, nis:mail.aliases
+
+
+ +

The pathname of the alias database file is controlled with the +alias_database configuration parameter. The value is system dependent. +Usually it is one of the following:

+ +
+
+/etc/postfix/main.cf:
+    alias_database = hash:/etc/aliases (4.4BSD, LINUX)
+    alias_database = dbm:/etc/aliases (4.3BSD, SYSV<4)
+    alias_database = dbm:/etc/mail/aliases (SYSV4)
+
+
+ +

An aliases(5) file can specify that mail should be delivered +to a local file, or to a command that receives the message in the +standard input stream. For security reasons, deliveries to command +and file destinations are performed with the rights of the alias +database owner. A default userid, default_privs, is used for +deliveries to commands or files in "root"-owned aliases.

+ +

Local per-user .forward files

+ +

With delivery via the local(8) delivery agent, users can control +their own mail delivery by specifying destinations in a file called +.forward in their home directories. The syntax of these files is +the same as with the local aliases(5) file, except that the left-hand +side of the alias (lookup key and colon) are not present.

+ +

Local catch-all address

+ +

When the local(8) delivery agent finds that a message recipient +does not exist, the message is normally returned to the sender ("user +unknown"). Sometimes it is desirable to forward mail for non-existing +recipients to another machine. For this purpose you can specify +an alternative destination with the luser_relay configuration +parameter.

+ +

Alternatively, mail for non-existent recipients can be delegated +to an entirely different message transport, as specified with the +fallback_transport configuration parameter. For details, see the +local(8) delivery agent documentation.

+ +

Note: if you use the luser_relay feature in order to receive +mail for non-UNIX accounts, then you must specify:

+ +
+
+/etc/postfix/main.cf:
+    local_recipient_maps =
+
+
+ +

(i.e. empty) in the main.cf file, otherwise the Postfix SMTP +server will reject mail for non-UNIX accounts with "User unknown +in local recipient table". See the LOCAL_RECIPIENT_README file +for more information on this. +

+ +

luser_relay can specify one address. It is subjected to "$name" +expansions. Examples:

+ +
+ +
+ +
$user@other.host
+ +

The bare username, without address extension, is prepended +to "@other.host". For example, mail for "username+foo" is sent to +"username@other.host".

+ +
$local@other.host
+ +

The entire original recipient localpart, including address +extension, is prepended to "@other.host". For example, mail for +"username+foo" is sent to "username+foo@other.host".

+ +
sysadmin+$user
+ +

The bare username, without address extension, is appended +to "sysadmin". For example, mail for "username+foo" is sent to +"sysadmin+username".

+ +
sysadmin+$local
+ +

The entire original recipient localpart, including address +extension, is appended to "sysadmin". For example, mail for +"username+foo" is sent to "sysadmin+username+foo".

+ +
+ +
+ +

Debugging your address manipulations

+ +

Postfix version 2.1 and later can +produce mail delivery reports for debugging purposes. These reports +not only show sender/recipient addresses after address rewriting +and alias expansion or forwarding, they also show information about +delivery to mailbox, delivery to non-Postfix command, responses +from remote SMTP servers, and so on.

+ +

Postfix can produce two types of mail delivery reports for +debugging:

+ + + +

These reports contain information that is generated by Postfix +delivery agents. Since these run as daemon processes and do not +interact with users directly, the result is sent as mail to the +sender of the test message. The format of these reports is practically +identical to that of ordinary non-delivery notifications.

+ +

As an example, below is the delivery report that is produced +with the command "sendmail -bv postfix-users@postfix.org". The +first part of the report contains human-readable text. In this +case, mail would be delivered via mail.cloud9.net, and the SMTP +server replies with "250 Ok". Other reports may show delivery +to mailbox, or delivery to non-Postfix command.

+ +
+
+Content-Description: Notification
+Content-Type: text/plain
+
+This is the mail system at host spike.porcupine.org.
+
+Enclosed is the mail delivery report that you requested.
+
+                        The mail system
+
+<postfix-users@postfix.org>: delivery via mail.cloud9.net[168.100.1.4]: 250 2.1.5 Ok
+
+
+ +

The second part of the report is in machine-readable form, and +includes the following information:

+ + + +

Some details depend on Postfix version. The example below is +for Postfix version 2.3 and later.

+ +
+
+Content-Description: Delivery report
+Content-Type: message/delivery-status
+
+Reporting-MTA: dns; spike.porcupine.org
+X-Postfix-Queue-ID: 84863BC0E5
+X-Postfix-Sender: rfc822; wietse@porcupine.org
+Arrival-Date: Sun, 26 Nov 2006 17:01:01 -0500 (EST)
+
+Final-Recipient: rfc822; postfix-users@postfix.org
+Action: deliverable
+Status: 2.1.5
+Remote-MTA: dns; mail.cloud9.net
+Diagnostic-Code: smtp; 250 2.1.5 Ok
+
+
+ +

The third part of the report contains the message that Postfix +would have delivered, including From: and To: message headers, so +that you can see any effects of address rewriting on those. Mail +submitted with "sendmail -bv" has no body content so none is shown +in the example below.

+ +
+
+Content-Description: Message
+Content-Type: message/rfc822
+
+Received: by spike.porcupine.org (Postfix, from userid 1001)
+        id 84863BC0E5; Sun, 26 Nov 2006 17:01:01 -0500 (EST)
+Subject: probe
+To: postfix-users@postfix.org
+Message-Id: <20061126220101.84863BC0E5@spike.porcupine.org>
+Date: Sun, 26 Nov 2006 17:01:01 -0500 (EST)
+From: wietse@porcupine.org (Wietse Venema)
+
+
+ + + + -- cgit v1.2.3