The bogofilter ./configure script cannot currently auto-detect thenon-standard install location of db3 or db4 on FreeBSD.To compile bogofilter on a stock FreeBSD 4.x with db3 or db4 installedvia port or package, try to re-run configure like this:env CPPFLAGS=-I/usr/local/include/db3 LIBS=-ldb3 LDFLAGS=-L/usr/local/lib \  sh ./configure --with-libdb-prefix=/usr/localReplace the two "db3" with "db4" if appropriate, and adjust all/usr/local occurrences if your PREFIX is not /usr/local.