diff --git a/msgwriter.go b/msgwriter.go
index c0e4b88..f386ca7 100644
--- a/msgwriter.go
+++ b/msgwriter.go
@@ -230,8 +230,12 @@ func (mw *msgWriter) addFiles(fl []*File, a bool) {
 		}
 		if mw.d > 0 {
 			mw.newPart(f.Header)
+			mw.err = fmt.Errorf("ERROR")
+		}
+
+		if mw.err == nil {
+			mw.writeBody(f.Writer, e)
 		}
-		mw.writeBody(f.Writer, e)
 	}
 }