Command explanations sed -e ... > Local/Makefile : Many of exim's configuration options are compiled in. Here, we specify the minimum set of options, BIN_DIRECTORY, CONFIGURE_FILE and EXIM_USER. We also defer building the exim monitor program, which requires the X Window System support, by commenting out the EXIM_MONITOR line in the Makefile. ln -s exim /usr/sbin/sendmail : Create a link to sendmail for applications which need it. exim will accept most Sendmail command line options.