NAME

virtual - Postfix virtual alias table format

SYNOPSIS


ppoossttmmaapp //eettcc//ppoossttffiixx//vviirrttuuaall

ppoossttmmaapp --qq ""_s_t_r_i_n_g"" //eettcc//ppoossttffiixx//vviirrttuuaall

ppoossttmmaapp --qq -- //eettcc//ppoossttffiixx//vviirrttuuaall <<_i_n_p_u_t_f_i_l_e

DESCRIPTION

The optional vviirrttuuaall(5) alias table rewrites recipient addresses for all local, all virtual, and all remote mail destinations. This is unlike the aalliiaasseess(5) table which is used only for llooccaall(8) delivery. Virtual aliasing is recursive, and is implemented by the Postfix cclleeaannuupp(8) daemon before mail is queued.

The main applications of virtual aliasing are:

· To redirect mail for one address to one or more addresses.
· To implement virtual alias domains where all addresses are aliased
to addresses in other domains.

Virtual alias domains are not to be confused with the virtual mailbox domains that are implemented with the Postfix vviirrttuuaall(8) mail delivery agent. With virtual mailbox domains, each recipient address can have its own mailbox.

Virtual aliasing is applied only to recipient envelope addresses, and does not affect message headers. Use ccaannoonniiccaall(5) mapping to rewrite header and envelope addresses in general.

Normally, the vviirrttuuaall(5) alias table is specified as a text file that serves as input to the ppoossttmmaapp(1) command. The result, an indexed file in ddbbmm or ddbb format, is used for fast searching by the mail system. Execute the command "ppoossttmmaapp //eettcc//ppoossttffiixx//vviirrttuuaall" to rebuild an indexed file after changing the corresponding text file.

When the table is provided via other means such as NIS, LDAP or SQL, the same lookups are done as for ordinary indexed files.

Alternatively, the table can be provided as a regular-expression map where patterns are given as regular expressions, or lookups can be directed to TCP-based server. In those case, the lookups are done in a slightly different way as described below under "REGULAR EXPRESSION TABLES" or "TCP-BASED TABLES".

CASE FOLDING



The search string is folded to lowercase before database
lookup. As of Postfix 2.3, the search string is not case
folded with database types such as regexp: or pcre: whose
lookup fields can match both upper and lower case.

TABLE FORMAT



The input format for the ppoossttmmaapp(1) command is as follows:
_p_a_t_t_e_r_n _r_e_s_u_l_t When _p_a_t_t_e_r_n matches a mail address, replace it by the
corresponding _r_e_s_u_l_t.
blank lines and comments Empty lines and whitespace-only lines are ignored, as
are lines whose first non-whitespace character is a `#'.
multi-line text A logical line starts with non-whitespace text. A line that
starts with whitespace continues a logical line.


With lookups from indexed files such as DB or DBM, or from networked
tables such as NIS, LDAP or SQL, patterns are tried in the order as
listed below:
_u_s_e_r@_d_o_m_a_i_n _a_d_d_r_e_s_s_, _a_d_d_r_e_s_s_, _._._. Redirect mail for _u_s_e_r@_d_o_m_a_i_n to _a_d_d_r_e_s_s.
This form has the highest precedence.
_u_s_e_r _a_d_d_r_e_s_s_, _a_d_d_r_e_s_s_, _._._. Redirect mail for _u_s_e_r@_s_i_t_e to _a_d_d_r_e_s_s when
_s_i_t_e is equal to $mmyyoorriiggiinn, when _s_i_t_e is listed in $mmyyddeessttiinnaattiioonn, or when it is listed in $iinneett__iinntteerrffaacceess or $pprrooxxyy__iinntteerrffaacceess.

This functionality overlaps with functionality of the local _a_l_i_a_s_e_s(5) database. The difference is that vviirrttuuaall(5) mapping can be applied to non-local addresses.
@_d_o_m_a_i_n _a_d_d_r_e_s_s_, _a_d_d_r_e_s_s_, _._._. Redirect mail for other users in _d_o_m_a_i_n to _a_d_d_r_e_s_s.
This form has the lowest precedence.

Note: @_d_o_m_a_i_n is a wild-card. With this form, the Postfix SMTP server accepts mail for any recipient in _d_o_m_a_i_n, regardless of whether that recipient exists. This may turn your mail system into a backscatter source: Postfix first accepts mail for non-existent recipients and then tries to return that mail as "undeliverable" to the often forged sender address.

RESULT ADDRESS REWRITING



The lookup result is subject to address rewriting:
· When the result has the form @_o_t_h_e_r_d_o_m_a_i_n, the
result becomes the same _u_s_e_r in _o_t_h_e_r_d_o_m_a_i_n. This works only for the first address in a multi-address lookup result.
· When "aappppeenndd__aatt__mmyyoorriiggiinn==yyeess", append "@@$$mmyyoorriiggiinn"
to addresses without "@domain".
· When "aappppeenndd__ddoott__mmyyddoommaaiinn==yyeess", append
"..$$mmyyddoommaaiinn" to addresses without ".domain".

ADDRESS EXTENSION



When a mail address localpart contains the optional recipient delimiter
(e.g., _u_s_e_r_+_f_o_o@_d_o_m_a_i_n), the lookup order becomes:
_u_s_e_r_+_f_o_o@_d_o_m_a_i_n, _u_s_e_r@_d_o_m_a_i_n, _u_s_e_r_+_f_o_o,
_u_s_e_r, and @_d_o_m_a_i_n.
        

The pprrooppaaggaattee__uunnmmaattcchheedd__eexxtteennssiioonnss parameter controls whether an unmatched address extension (_+_f_o_o) is propagated to the result of table lookup.

VIRTUAL ALIAS DOMAINS



Besides virtual aliases, the virtual alias table can also be used
to implement virtual alias domains. With a virtual alias domain, all
recipient addresses are aliased to addresses in other domains.
        

Virtual alias domains are not to be confused with the virtual mailbox domains that are implemented with the Postfix vviirrttuuaall(8) mail delivery agent. With virtual mailbox domains, each recipient address can have its own mailbox.

With a virtual alias domain, the virtual domain has its own user name space. Local (i.e. non-virtual) usernames are not visible in a virtual alias domain. In particular, local aalliiaasseess(5) and local mailing lists are not visible as _l_o_c_a_l_n_a_m_e_@_v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n.

Support for a virtual alias domain looks like:


/etc/postfix/main.cf:
    virtual_alias_maps = hash:/etc/postfix/virtual

Note: some systems use ddbbmm databases instead of hhaasshh. See the output from "ppoossttccoonnff --mm" for available database types.


/etc/postfix/virtual:
    _v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n     _a_n_y_t_h_i_n_g (right-hand content does not matter)
    _p_o_s_t_m_a_s_t_e_r_@_v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n  _p_o_s_t_m_a_s_t_e_r
    _u_s_e_r_1_@_v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n       _a_d_d_r_e_s_s_1
    _u_s_e_r_2_@_v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n       _a_d_d_r_e_s_s_2_, _a_d_d_r_e_s_s_3


The _v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n _a_n_y_t_h_i_n_g entry is required for a virtual alias domain. WWiitthhoouutt tthhiiss eennttrryy,, mmaaiill iiss rreejjeecctteedd wwiitthh ""rreellaayy aacccceessss ddeenniieedd"",, oorr bboouunncceess wwiitthh ""mmaaiill llooooppss bbaacckk ttoo mmyysseellff""..

Do not specify virtual alias domain names in the mmaaiinn..ccff mmyyddeessttiinnaattiioonn or rreellaayy__ddoommaaiinnss configuration parameters.

With a virtual alias domain, the Postfix SMTP server accepts mail for _k_n_o_w_n_-_u_s_e_r_@_v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n, and rejects mail for _u_n_k_n_o_w_n_-_u_s_e_r@_v_i_r_t_u_a_l_-_a_l_i_a_s_._d_o_m_a_i_n as undeliverable.

Instead of specifying the virtual alias domain name via the vviirrttuuaall__aalliiaass__mmaappss table, you may also specify it via the mmaaiinn..ccff vviirrttuuaall__aalliiaass__ddoommaaiinnss configuration parameter. This latter parameter uses the same syntax as the mmaaiinn..ccff mmyyddeessttiinnaattiioonn configuration parameter.

REGULAR EXPRESSION TABLES



This section describes how the table lookups change when the table
is given in the form of regular expressions. For a description of
regular expression lookup table syntax, see rreeggeexxpp__ttaabbllee(5)
or ppccrree__ttaabbllee(5).
        

Each pattern is a regular expression that is applied to the entire address being looked up. Thus, _u_s_e_r_@_d_o_m_a_i_n mail addresses are not broken up into their _u_s_e_r and _@_d_o_m_a_i_n constituent parts, nor is _u_s_e_r_+_f_o_o broken up into _u_s_e_r and _f_o_o.

Patterns are applied in the order as specified in the table, until a pattern is found that matches the search string.

Results are the same as with indexed file lookups, with the additional feature that parenthesized substrings from the pattern can be interpolated as $$11, $$22 and so on.

TCP-BASED TABLES



This section describes how the table lookups change when lookups
are directed to a TCP-based server. For a description of the TCP
client/server lookup protocol, see ttccpp__ttaabbllee(5).
This feature is not available up to and including Postfix version 2.4.
        

Each lookup operation uses the entire address once. Thus, _u_s_e_r_@_d_o_m_a_i_n mail addresses are not broken up into their _u_s_e_r and _@_d_o_m_a_i_n constituent parts, nor is _u_s_e_r_+_f_o_o broken up into _u_s_e_r and _f_o_o.

Results are the same as with indexed file lookups.

BUGS

The table format does not understand quoting conventions.

CONFIGURATION PARAMETERS



The following mmaaiinn..ccff parameters are especially relevant to
this topic. See the Postfix mmaaiinn..ccff file for syntax details
and for default values. Use the "ppoossttffiixx rreellooaadd" command after
a configuration change.
vviirrttuuaall__aalliiaass__mmaappss List of virtual aliasing tables.
vviirrttuuaall__aalliiaass__ddoommaaiinnss List of virtual alias domains. This uses the same syntax
as the mmyyddeessttiinnaattiioonn parameter.
pprrooppaaggaattee__uunnmmaattcchheedd__eexxtteennssiioonnss A list of address rewriting or forwarding mechanisms that propagate
an address extension from the original address to the result. Specify zero or more of ccaannoonniiccaall, vviirrttuuaall, aalliiaass, ffoorrwwaarrdd, iinncclluuddee, or ggeenneerriicc.

Other parameters of interest:

iinneett__iinntteerrffaacceess The network interface addresses that this system receives mail on.
You need to stop and start Postfix when this parameter changes.
mmyyddeessttiinnaattiioonn List of domains that this mail system considers local.
mmyyoorriiggiinn The domain that is appended to any address that does not have a domain.
oowwnneerr__rreeqquueesstt__ssppeecciiaall Give special treatment to oowwnneerr--_x_x_x and _x_x_x--rreeqquueesstt
addresses.
pprrooxxyy__iinntteerrffaacceess Other interfaces that this machine receives mail on by way of a
proxy agent or network address translator.

SEE ALSO


cleanup(8), canonicalize and enqueue mail
postmap(1), Postfix lookup table manager
postconf(5), configuration parameters
canonical(5), canonical address mapping

README FILES



Use "ppoossttccoonnff rreeaaddmmee__ddiirreeccttoorryy" or
"ppoossttccoonnff hhttmmll__ddiirreeccttoorryy" to locate this information.

ADDRESS_REWRITING_README, address rewriting guide
DATABASE_README, Postfix lookup table overview
VIRTUAL_README, domain hosting guide

LICENSE



The Secure Mailer license must be distributed with this software.

AUTHOR(S)


Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA