fix sa hook

contrib/backends/srndv2/src/srnd/spam.go

@@ -35,6 +35,7 @@ func (sp *SpamFilter) Rewrite(msg io.Reader, out io.WriteCloser) error {
 	if err != nil {
 		return err
 	}
+	io.WriteString(c, "SPAMC/1.5\r\n")
 	io.CopyBuffer(c, msg, buff[:])
 	c.CloseWrite()
 	_, err = io.CopyBuffer(out, c, buff[:])