sendmail, 4th Edition

FEATURE(limited_masquerade)

Only masquerade MASQUERADE_DOMAIN hosts V8.8 and later

Ordinarily, addresses can be masqueraded if they are unqualified (lack a domain part) or if they match any hostname in $=w ($=w on page 876) or in the special class defined by the MASQUERADE_DOMAIN mc macro (MASQUERADE_DOMAIN mc Macro on page 600). Masquerading replaces the hostname part of an address with the fully qualified hostname defined by MASQUERADE_AS.

Some sites handle mail for multiple domains. For these sites, it is important to recognize all incoming mail as local via $=w. On the other hand, only a subset of the hosts in $=w should be masqueraded. Consider, for example, the host our.domain that receives mail for the domains his.domain and her.domain:

Cw our.domain his.domain her.domain

In this scenario, we want all but her.domain to be masqueraded as our.domain. The way to create such exceptions is with FEATURE(limited_masquerade).

FEATURE(limited_masquerade) causes masquerading to be based only on the special class defined by the MASQUERADE_DOMAIN mc macro (MASQUERADE_DOMAIN mc Macro on page 600) and not $=w. You use limited_masquerade like this:

MASQUERADE_AS(`our.domain')
FEATURE(`limited_masquerade')
LOCAL_DOMAIN(`our.domain his.domain her.domain')
MASQUERADE_DOMAIN(`our.domain his.domain')

Here, MASQUERADE_AS is declared first to define how masqueraded domains should be rewritten. Then, FEATURE(limited_masquerade) is declared. The LOCAL_DOMAIN declares all three domains to be recognized ...