''${if_name}'' '''


The name of the receive interface V8.10 and above

Network interfaces can have one or more addresses associated with each interface, and each address will have a hostname associated with it. For example, on a machine with two interfaces, the one connected to the outside world might have the name host.your.domain, whereas the interface that is connected to the internal network might have the name host.sub.your.domain.

When sendmail first starts up as a listening daemon, it binds to a port on all interfaces or on a particular interface (See this section). It then waits to accept connections from hosts or programs (clients) that wish to route mail through it.

When a client connects to the local machine, sendmail records the local IP address of the connected-to interface in the ${if_addr} macro (${if_addr}), the family of that address in the ${if_family} macro (${if_family}), and the name associated with the interface over which the connection was made in this ${if_name} macro. If the connection is on the local host's loopback interface, the ${if_name} macro is undefined.

The ${if_name} macro can be useful when you are set up to do virtual hosting. You can have sendmail give its greeting message in a form that makes it appear to be the host that is associated with the interface:

define(`confSMTP_LOGIN_MSG', `$?{if_name}${if_name}$|$j$. ESMTP MTA')

Here, we define sendmail's initial greeting message with the SmtpGreetingMessage option (SmtpGreetingMessage). It has one of two forms, depending on whether the ${if_name} contains a value. The conditional macro $? looks up the value in ${if_name}. If that value is non-NULL, the value in ${if_name} is printed. Otherwise, (the $|) the canonical local hostname is printed (the $j). The $. terminates the if test, and a literal ESMTP MTA is always printed:

220 virtual.domain ESMTP MTA     the outside interface
220 host.your.domain ESMTP MTA   the loopback interface

${if_name} is transient. If it is defined in the configuration file or in the command line, that definition can be ignored by sendmail. Note that a $& prefix is necessary when you reference this macro in rules (that is, use $&{if_name}, not ${if_name}).

    Part I: Build and Install
    Part II: Administration
    Part III: The Configuration File
    Chapter 21. The D (Define a Macro) Configuration Command
    Chapter 24. The O (Options) Configuration Command