Delivering to Local Recipient

Typically, some early rules in the parse rule set 0 are intended to detect addresses that should be delivered locally. A rule that accomplishes that end might look like this:

R $+ <@ $w>          $#local $:$1                 local address

Here, the $w sendmail macro is the name of the local host. Note that the RHS strips the focused host part from the username.

At some sites, the local host can be known by any of several names. A rule to handle such hosts would begin with a class declaration that adds those names to the class w (such as in the first line here):

Cw font-server fax printer3
R $+ <@ $=w>        $#local $:$1                 local address

The class w is special because it is the one to which sendmail automatically appends the alternative name of the local host. This class declaration line adds names that sendmail might not automatically detect. Usually, such a declaration would be near the top of the configuration file rather than in the parse rule set 0, but technically it can appear anywhere in the file. This rule looks to see whether an address contains any of the names in class w. If it does, the $=w in the lefthand side (LHS) matches, and the RHS selects the local delivery agent.

On central mail-server machines, the parse rule set 0 might also have to match from a list of hosts for which the central server is an MX recipient machine (FEATURE(use_cw_file) on page 643).

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