ADDRESS_REWRITING_README [plain text]
PPoossttffiixx AAddddrreessss RReewwrriittiinngg
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PPoossttffiixx aaddddrreessss rreewwrriittiinngg ppuurrppoossee
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:
* Transform an incomplete address into a complete address. For example,
transform "username" into "username@example.com", or transform
"username@hostname" into "username@hostname.example.com".
* Replace an address by an equivalent address. For example, replace
"username@example.com" by "firstname.lastname@example.com" when sending
mail, and do the reverse transformation when receiving mail.
* Replace an address by multiple addresses. For example, replace the address
of an alias by the addresses listed under that alias.
* Determine how and where to deliver mail for a specific address. For
example, deliver mail for "username@example.com" with the smtp(8) delivery
agent, to the hosts that are listed in the DNS as the mail servers for the
domain "example.com".
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:
* Postfix address rewriting overview
* Address rewriting when mail is received
o Rewrite addresses to standard form
o Canonical address mapping
o Address masquerading
o Automatic BCC recipients
o Virtual aliasing
* Address rewriting when mail is delivered
o Resolve address to destination
o Mail transport switch
o Relocated users table
o Local alias database
o Local per-user .forward files
o Local catch-all address
* Debugging your address manipulations
PPoossttffiixx aaddddrreessss rreewwrriittiinngg oovveerrvviieeww
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- trivial-
rewrite(8) rewrite(8)
(std form) (resolve)
^ | ^ |
| v | v
smtpd(8) smtp(8)
qmqpd(8) >- cleanup(8) -> incoming -> active -> qmgr(8) -< lmtp(8)
pickup(8) local(8)
^ ^ |
| | v
bounces
forwarding deferred
notices
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.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
|AAddddrreessss |SSccooppee|DDaaeemmoonn |GGlloobbaall ttuurrnn--oonn |SSeelleeccttiivvee ttuurrnn--ooffff |
|mmaanniippuullaattiioonn| | |ccoonnttrrooll |ccoonnttrrooll |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Rewrite | |trivial-|append_at_myorigin, | |
|addresses to|all |rewrite |append_dot_mydomain,|none |
|standard |mail |(8) |swap_bangpath, | |
|form | | |allow_percent_hack | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Canonical |all |cleanup | | |
|address |mail |(8) |canonical_maps |receive_override_options|
|mapping | | | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Address |all |cleanup |masquerade_domains |receive_override_options|
|masquerading|mail |(8) | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Automatic |new |cleanup |always_bcc, | |
|BCC |mail |(8) |sender_bcc_maps, |receive_override_options|
|recipients | | |recipient_bcc_maps | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Virtual |all |cleanup |virtual_alias_maps |receive_override_options|
|aliasing |mail |(8) | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Resolve |all |trivial-| | |
|address to |mail |rewrite |none |none |
|destination | |(8) | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Mail |all |trivial-| | |
|transport |mail |rewrite |transport_maps |none |
|switch | |(8) | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Relocated |all |trivial-| | |
|users table |mail |rewrite |relocated_maps |none |
| | |(8) | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Local alias |all |local(8)|alias_maps |none |
|database |mail | | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Local per- | | | | |
|user |all |local(8)|forward_path |none |
|.forward |mail | | | |
|files | | | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
|Local catch-|all |local(8)|luser_relay |none |
|all address |mail | | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _|_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
AAddddrreessss rreewwrriittiinngg wwhheenn mmaaiill iiss rreecceeiivveedd
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
* Canonical address mapping
* Address masquerading
* Automatic BCC recipients
* Virtual aliasing
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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.
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.
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".
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".
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.
Some will argue that rewriting "host" to "host.$mydomain" is bad. That
is why it can be turned off. Others like the convenience of having the
local 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.
CCaannoonniiccaall aaddddrreessss mmaappppiinngg
The cleanup(8) daemon uses the canonical(5) tables to rewrite all addresses in
message envelopes and in message headers. This 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.
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:
:10026 inet n - n - - smtpd
-o receive_override_options=no_address_mapping
Note: do not specify whitespace around the "=" here.
AAddddrreessss mmaassqquueerraaddiinngg
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.
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:
:10026 inet n - n - - smtpd
-o receive_override_options=no_address_mapping
Note: do not specify whitespace around the "=" here.
AAuuttoommaattiicc BBCCCC rreecciippiieennttss
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:
:10026 inet n - n - - smtpd
-o receive_override_options=no_address_mapping
Note: do not specify whitespace around the "=" here.
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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).
Note: automatic BCC recipients are produced only for new mail. To avoid mailer
loops, automatic BCC recipients are not generated for mail that is forwarded
internally, and are not generated for mail that is generated by Postfix itself.
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:
:10026 inet n - n - - smtpd
-o receive_override_options=no_address_mapping
Note: do not specify whitespace around the "=" here.
At this point the message is ready to be stored into the Postfix incoming
queue.
AAddddrreessss rreewwrriittiinngg wwhheenn mmaaiill iiss ddeelliivveerreedd
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:
* Resolve address to destination
* Mail transport switch
* Relocated users table
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 local(8) delivery agent:
* Local alias database
* Local per-user .forward files
* Local catch-all address
The remainder of this document presents each address manipulation step in more
detail, with specific examples or with pointers to documentation with examples.
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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.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
|DDeessttiinnaattiioonn ddoommaaiinn lliisstt |DDeeffaauulltt ddeelliivveerryy mmeetthhoodd|AAvvaaiillaabbiilliittyy|
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ |
|$mydestination, $inet_interfaces,|$local_transport |Postfix 1.0 |
|$proxy_interfaces | | |
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ |
|$virtual_mailbox_domains |$virtual_transport |Postfix 2.0 |
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ |
|$relay_domains |$relay_transport |Postfix 2.0 |
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ |
|none |$default_transport |Postfix 1.0 |
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ |
MMaaiill ttrraannssppoorrtt sswwiittcchh
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) 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
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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.
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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.
LLooccaall ppeerr--uusseerr ..ffoorrwwaarrdd ffiilleess
With delivery via the local(8) deliver 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.
LLooccaall ccaattcchh--aallll aaddddrreessss
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".
DDeebbuuggggiinngg yyoouurr aaddddrreessss mmaanniippuullaattiioonnss
With Postfix version 2.1 and later you can ask Postfix to 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:
* What-if: report what would happen, but do not actually deliver mail. This
mode of operation is requested with:
$ //uussrr//ssbbiinn//sseennddmmaaiill --bbvv aaddddrreessss......
Mail Delivery Status Report will be mailed to <your login name>.
* What happened: deliver mail and report successes and/or failures, including
replies from remote SMTP servers. This mode of operation is requested with:
$ //uussrr//ssbbiinn//sseennddmmaaiill --vv aaddddrreessss......
Mail Delivery Status Report will be mailed to <your login name>.
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 Postfix program at host spike.porcupine.org.
Enclosed is the mail delivery report that you requested.
The Postfix program
<postfix-users@postfix.org>: delivery via mail.cloud9.net[168.100.1.4]: 250
Ok
The second part of the report is in machine-readable form, and includes the
following information:
* The envelope sender address (wietse@porcupine.org).
* The envelope recipient address (postfix-users@postfix.org). If the
recipient address was changed by Postfix then Postfix also includes the
original recipient address.
* The delivery status.
Some details are still preliminary and will change as Postfix implements the
DSN (delivery status notification) standards.
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: Tue, 13 Apr 2004 19:27:43 -0400 (EDT)
Final-Recipient: rfc822; postfix-users@postfix.org
Action: deliverable
Status: 2.0.0
Diagnostic-Code: X-Postfix; delivery via mail.cloud9.net[168.100.1.4]: 250
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; Tue, 13 Apr 2004 19:27:43 -0400 (EDT)
Subject: probe
To: postfix-users@postfix.org
Message-Id: <20040413232743.84863BC0E5@spike.porcupine.org>
Date: Tue, 13 Apr 2004 19:27:43 -0400 (EDT)
From: wietse@porcupine.org (Wietse Venema)