function mail_encode($str, $eol = "\r\n")
{
	// define start delimimter, end delimiter and spacer
	$start = "=?UTF-8?B?";
	$end = "?=";
	$delimiter = "$eol ";

	// Maximum length is 75. $split_length *must* be a multiple of 4, but <= 75 - strlen($start . $delimiter . $end)!!!
	$split_length = 60;
	$encoded_str = base64_encode($str);

	// If encoded string meets the limits, we just return with the correct data.
	if (strlen($encoded_str) <= $split_length)
	{
		return $start . $encoded_str . $end;
	}

	// If there is only ASCII data, we just return what we want, correctly splitting the lines.
	if (strlen($str) === utf8_strlen($str))
	{
		return $start . implode($end . $delimiter . $start, str_split($encoded_str, $split_length)) . $end;
	}

	// UTF-8 data, compose encoded lines
	$array = utf8_str_split($str);
	$str = '';

	while (sizeof($array))
	{
		$text = '';

		while (sizeof($array) && intval((strlen($text . $array[0]) + 2) / 3) << 2 <= $split_length)
		{
			$text .= array_shift($array);
		}

		$str .= $start . base64_encode($text) . $end . $delimiter;
	}

	return substr($str, 0, -strlen($delimiter));
}