ClamAV $\ge0.95$ includes a new, redesigned clamav-milter. The most notable difference is that the internal mode has been dropped and now a working clamd companion is required. The second important difference is that now the milter has got its own configuration and log files.

To compile ClamAV with the clamav-milter just run ./configure --enable-milter and make as usual. In order to use the '-enable-milter' option with 'configure', your system MUST have the milter library installed. If you use the '-enable-milter' option without the library being installed, you will most likely see output like this during 'configure':
        checking for libiconv_open in -liconv... no
        checking for iconv... yes
        checking whether in_port_t is defined... yes
        checking for in_addr_t definition... yes
        checking for mi_stop in -lmilter... no
        checking for library containing strlcpy... no
        checking for mi_stop in -lmilter... no
        configure: error: Cannot find libmilter
At which point the 'configure' script will stop processing.

Please consult your MTA's manual on how to connect ClamAV with the milter.

Cisco 2016-04-21