If a MASQUERADE_AS domain is defined,
that name replaces any sender addresses, the domain part of which is
listed either by MASQUERADE_DOMAIN (Section 4.4.3), or
in the $=w class ($=w).
The allmasquerade feature causes header recipient
addresses to also have that treatment.
But note that this feature can be extremely risky and that it should
be used only if the MASQUERADE_AS host has an
aliases file that is a superset of all
aliases files and a passwd
file that is a superset of all passwd files at
your site. To illustrate the risk, consider a situation in which the
masquerade host is named hub.domain and mail is
being sent from the local workstation. If a local alias exists on the
thishost-usersthat does not also exist on
the masquerade host, this allmasquerade feature
will cause the To: header to go out as:
Here, the address thishost-users does not exist
on the masquerade host (or worse, possibly as an address somewhere
out on the Internet), and as a consequence, replies to messages
containing this header will bounce.
The form for the allmasquerade feature is:
Note that MASQUERADE_AS (Section 4.4.2) must also be
defined and must contain a fully qualified hostname.