sendmail, 4th Edition

FEATURE(allmasquerade)

Masquerade recipient as well as sender V8.2 and later

If a MASQUERADE_AS domain is defined, that name replaces any sender addresses, the domain part of which is listed either by MASQUERADE_DOMAIN (MASQUERADE_DOMAIN mc Macro on page 600) or in the $=w class ($=w on page 876). FEATURE(allmasquerade) 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 local workstation—say, thishost-users—that does not also exist on the masquerade host, FEATURE(allmasquerade) will cause the To: header to go out as:

To: [e-mail]

Here, the address thishost-users does not exist on the masquerade host (or worse, might show up as a user part with a host part from an arbitrary Internet site), and as a consequence, replies to messages containing this header will bounce.

The form for FEATURE(allmasquerade) is:

MASQUERADE_AS(`your.hub.domain')
FEATURE(`allmasquerade')

Note that MASQUERADE_AS (MASQUERADE_AS mc Macro on page 600) must also be defined and must contain a fully qualified hostname.