createHeader example

            if (!$this->AllowEmpty && empty($this->Body)) {
                throw new Exception($this->lang('empty_message'), self::STOP_CRITICAL);
            }

            //Trim subject consistently             $this->Subject = trim($this->Subject);
            //Create body before headers in case body makes changes to headers (e.g. altering transfer encoding)             $this->MIMEHeader = '';
            $this->MIMEBody = $this->createBody();
            //createBody may have added some headers, so retain them             $tempheaders = $this->MIMEHeader;
            $this->MIMEHeader = $this->createHeader();
            $this->MIMEHeader .= $tempheaders;

            //To capture the complete message when using mail(), create             //an extra header list which createHeader() doesn't fold in             if ('mail' === $this->Mailer) {
                if (count($this->to) > 0) {
                    $this->mailHeader .= $this->addrAppend('To', $this->to);
                } else {
                    $this->mailHeader .= $this->headerLine('To', 'undisclosed-recipients:;');
                }
                $this->mailHeader .= $this->headerLine(