Ordinarily, the MASQUERADE_AS mc configuration macro (Section 4.4.2) causes header, envelope, sender, and recipient addresses to appear as though they were sent from the masquerade host. Sometimes it is desirable to perform masquerading only when mail is sent offsite, and not to masquerade when mail is sent from one user to another locally.

For just such situations, the local_no_masquerade feature is available. You declare it like this:

FEATURE(`local_no_masquerade')

You must make this declaration before you declare the local delivery agent. If you mistakenly declare local first, like this:

MAILER(`local')                  wrong, local must not be first
FEATURE(`local_no_masquerade')

you will see the following error, and your configuration file will be incomplete:

*** MAILER(`local') must appear after FEATURE(`local_no_masquerade')