remove enrypted part nesting

Author: huehnerhose

writeto.go

@@ -3,7 +3,6 @@ package mail
 import (
 	"encoding/base64"
 	"errors"
-	"fmt"
 	"io"
 	"mime"
 	"mime/multipart"
@@ -55,13 +54,7 @@ func (w *messageWriter) writeMessage(m *Message) (int64, error) {
 	w.writeHeaders(m.header)
 
 	if m.isSetProtocol() && !m.isSecuredMIME() { // fetch the enveloped case
-		mime := fmt.Sprintf("encrypted;\r\n protocol=\"%s\"", m.protocol)
-		w.openMultipart(mime, m.boundary)
-
-		w.writePart(m.controlPart, m.charset)
 		w.writePart(m.protectedPart, m.charset)
-
-		w.closeMultipart()
 		return w.n, w.err
 	}