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 email@example.com
by his ISP mail address, replaces firstname.lastname@example.org 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).
smtp_generic_maps = hash:/etc/postfix/generic
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”.
A genericstable feature appears in the Sendmail MTA.
This feature is available in Postfix 2.2 and later.
IBM T.J. Watson Research
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Yorktown Heights, NY 10598, USA