CAllMailMessage::getClearBody

static function getClearBody(string $body): string
{
	//todo merge with BitrixMainMailMail::convertBodyHtmlToText
	// get  inner html if exists
	$innerBody = trim(preg_replace('/(.*?]*>)(.*?)(.*)/is', '$2', $body));
	$body = $innerBody ?: $body;

	// modify links to text version
	$body = preg_replace_callback(
		"%]*?href=(['"])(?[^1]*?)(?1)[^>]*?>(?.*?)%ims",
		function ($matches)
		{
			$href = $matches['href'];
			$text = trim($matches['text']);
			if (!$href)
			{
				return $matches[0];
			}
			$text = strip_tags($text);
			return ($text ? "$text:" : '') ."n$hrefn";
		},
		$body
	);

	// change 
 to new line
	$body = preg_replace('//i', "n", $body);

	$body = preg_replace('|(]*>)(.*?)()|isU', '', $body);
	$body = preg_replace('|(]*>)(.*?)()|isU', '', $body);

	// remove tags
	$body = strip_tags($body);

	// format text to the left side
	$lines = [];
	foreach (explode("n", trim($body)) as $line)
	{
		$lines[] = trim($line);
	}

	// remove redundant new lines
	$body = preg_replace("/[\n]{2,}/", "nn", implode("n", $lines));

	// remove redundant spaces
	$body = preg_replace("/[ \t]{2,}/", "  ", $body);

	// decode html-entities
	return html_entity_decode($body);
}