Use application/octet-stream as default MIME type

src/fmail.c

@@ -388,13 +388,20 @@ initialize_magic(void)
 static void
 process_attachment(const char *filename, magic_t ctx, FILE *out)
 {
-    const char *mime, *last_eq;
+    const char *mime;
     int binary;
     FILE *f;
 
-    mime = magic_file(ctx, filename);
-    last_eq = strrchr(mime, '=');
-    binary = strcmp(last_eq, "=binary") ? 0 : 1;
+    if ( (mime = magic_file(ctx, filename)) ) {
+        const char *last_eq;
+
+        last_eq = strrchr(mime, '=');
+        binary = strcmp(last_eq, "=binary") ? 0 : 1;
+    }
+    else {
+        mime = "application/octet-stream";
+        binary = 1;
+    }
 
     fprintf(out, "Content-Type: %s\r\n", mime);
     fprintf(out, "Content-Transfer-Encoding: %s\r\n", binary ? "base64" : "quoted-printable");