isPrintable example

/** * Encode header fields * * Encodes header content according to RFC1522 if it contains non-printable * characters. * * @param string $value * @return string */
    protected function _encodeHeader($value)
    {
        if (Zend_Mime::isPrintable($value) === false) {
            if ($this->getHeaderEncoding() === Zend_Mime::ENCODING_QUOTEDPRINTABLE) {
                $value = Zend_Mime::encodeQuotedPrintableHeader($value, $this->getCharset(), Zend_Mime::LINELENGTH, Zend_Mime::LINEEND);
            } else {
                $value = Zend_Mime::encodeBase64Header($value, $this->getCharset(), Zend_Mime::LINELENGTH, Zend_Mime::LINEEND);
            }
        }

        return $value;
    }

    /** * Add a header to the message * * Adds a header to this message. If append is true and the header already * exists, raises a flag indicating that the header should be appended. * * @param string $headerName * @param string $value * @param bool $append */