Thanks everybody for giving me clues about the making of a popserver.
Al the post I received where giving me the same clue.
So I changed:
#LDADD+= -lcrypt -lndbm
in the make.44bsd file and it workt.
I took away the -Indbm because that did not work either.
But I have a full working popserver now.
PS, Is it possible to use the BSF machine as a gateway on a network and use
only one ip number?
All machines using the gateway are having the same ip number?