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
The main applications of virtual aliasing are:
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".
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.
The input format for the ppoossttmmaapp(1) command is as follows:
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:
The lookup result is subject to address rewriting:
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.
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
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.
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.
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.
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.
Other parameters of interest:
cleanup(8), canonicalize and enqueue mail postmap(1), Postfix lookup table manager postconf(5), configuration parameters canonical(5), canonical address mapping
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
The Secure Mailer license must be distributed with this software.
Wietse Venema IBM T.J. Watson Research P.O. Box 704 Yorktown Heights, NY 10598, USA