diff -Naur proxsmtp-1.6-orig/configure.in proxsmtp-1.6/configure.in
--- proxsmtp-1.6-orig/configure.in	2009-08-13 11:25:29.000000000 +0200
+++ proxsmtp-1.6/configure.in	2009-08-13 11:31:27.000000000 +0200
@@ -86,6 +86,7 @@
    #ifdef HAVE_LIMITS_H
    #include <limits.h>
    #endif
+   #include <netinet/in.h>
    ]] )
 
 # Checks for typedefs, structures, and compiler characteristics.