Sendmail+IDA provides a number of tables that allow you to override the default behavior of sendmail (specified in the sendmail.m4 file) and define special behavior for unique situations, remote systems, and networks. These tables are post-processed with dbm using the Makefile provided with the distribution.
Most sites will need few, if any, of these tables. If your site does not require these tables, the easiest thing is probably to make them zero length files (with the touch command) and use the default Makefile in LIBDIR rather than editing the Makefile itself.