FEATURE(limited_masquerade)

FEATURE(limited_masquerade)

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Only masquerade MASQUERADE_DOMAIN hosts

V8.8 and above

Ordinarily, addresses can be masqueraded if they are unqualified (lack a domain part) or if they match any hostname in $=w ($=w) or in the special class defined by the MASQUERADE_DOMAIN mc macro (Section 4.4.3). 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 the limited_masquerade feature.

The limited_masquerade feature causes masquerading to be based only on the special class defined by the MASQUERADE_DOMAIN mc macro (Section 4.4.3), 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, the limited_masquerade feature is declared. The LOCAL_DOMAIN ($=w) declares all three domains to be recognized as local (that is, it adds them to the class $=w ). Finally, MASQUERADE_DOMAIN (Section 4.4.3) adds only the hosts that you wish masqueraded to the special class. Specifically, the special class omits the her.domain .

The limited_masquerade feature causes sendmail to masquerade the hosts in the special class defined by the MASQUERADE_DOMAIN mc macro, without the normal masquerading of the hosts in $=w too. Note that MASQUERADE_DOMAIN is also used to list the domains for the masquerade_entire_domain feature.