It has been taken from man – an interface to the on-line reference manuals.
The following shows a generic mapping with an indexed file. 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).
/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
Execute the command “postmap /etc/postfix/generic” whenever the table
is changed. Instead of hash, some systems use dbm database files. To
find out what tables your system supports use the command “postconf -m”.
HISTORY
A genericstable feature appears in the Sendmail MTA.
This feature is available in Postfix 2.2 and later.
AUTHOR(S)
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA