extern BOOL filter_runtest(int, uschar *, BOOL, BOOL);
extern BOOL filter_system_interpret(address_item **, uschar **);
+extern uschar * fn_hdrs_added(void);
+
extern void header_add(int, const char *, ...);
extern int header_checkname(header_line *, BOOL);
extern BOOL header_match(uschar *, BOOL, BOOL, string_item *, int, ...);