PHPMailer::getBoundary( string $boundary, string $charSet, string $contentType, string $encoding ): string

3361    protected function getBoundary($boundary, $charSet, $contentType, $encoding)3362    {3363        $result = '';3364        if ('' === $charSet) {3365            $charSet = $this->CharSet;3366        }3367        if ('' === $contentType) {3368            $contentType = $this->ContentType;3369        }3370        if ('' === $encoding) {3371            $encoding = $this->Encoding;3372        }3373        $result .= $this->textLine('--' . $boundary);3374        $result .= sprintf('Content-Type: %s; charset=%s', $contentType, $charSet);3375        $result .= static::$LE;3376        //RFC1341 part 5 says 7bit is assumed if not specified3377        if (static::ENCODING_7BIT !== $encoding) {3378            $result .= $this->headerLine('Content-Transfer-Encoding', $encoding);3379        }3380        $result .= static::$LE;3381 3382        return $result;3383    }