diff -ruN tpop3d-cvs/configure.in tpop3d/configure.in
--- tpop3d-cvs/configure.in	2003-01-10 00:20:23.000000000 +0100
+++ tpop3d/configure.in	2003-07-13 13:39:10.000000000 +0200
@@ -337,6 +337,18 @@
     AC_DEFINE(AUTH_PERL,1,[Use an embedded perl interpreter for authentication.])
 fi
 
+if test x"$enable_auth_pam" != x"yes" \
+&& test x"$enable_auth_passwd" != x"yes" \
+&& test x"$enable_shadow" != x"yes" \
+&& test x"$enable_auth_mysql" != x"yes" \
+&& test x"$enable_auth_ldap" != x"yes" \
+&& test x"$enable_auth_flatfile" != x"yes" \
+&& test x"$enable_auth_other" != x"yes" \
+&& test x"$enable_auth_perl" != x"yes"
+then
+    AC_MSG_ERROR([No authentication driver is enabled. At least one is required.])
+fi
+
 dnl Mailbox drivers
 if test x"$enable_mbox_bsd" = x"yes"
 then
@@ -478,10 +490,7 @@
 fi
 
 # Some machines have crypt(3) in libcrypt; test for this.
-if test x"$enable_auth_passwd" = x"yes" || test x"$enable_shadow" = x"yes" || test x"$enable_auth_mysql" = x"yes" || test x"$enable_auth_flatfile" = x"yes"
-then
-    AC_CHECK_LIB(crypt, crypt, , )
-fi
+AC_CHECK_LIB(crypt, crypt, , )
 
 # Some machines have dlopen etc. in libdl, and these are needed for PAM.
 if test x"$enable_auth_pam" = x"yes"