diff -upr mailx-12.5.orig/names.c mailx-12.5/names.c

--- mailx-12.5.orig/names.c	2006-03-04 01:32:16.000000000 +0100

+++ mailx-12.5/names.c	2012-11-01 15:28:43.883573793 +0100

@@ -357,7 +357,7 @@ outof(struct name *names, FILE *fo, stru

 			free_child(pid);

 		} else {

 			int f;

-			if ((fout = Zopen(fname, "a", NULL)) == NULL) {

+			if ((fname == NULL) || ((fout = Zopen(fname, "a", NULL)) == NULL)) {

 				perror(fname);

 				senderr++;

 				goto cant;