sanitize email.php

sanitize_email

function sanitize_email( $content ) {
	$data = array();
	foreach ( ( explode(' ',$content) ) as $address) {
		$email = filter_var($address,FILTER_VALIDATE_EMAIL);
		if ( $email ) {
			$email = preg_replace('/\./', '[dot]', $email);
			$email = preg_replace('/\@/', '[at]', $email);
			$data[] = $email;
		}
		else {
	    		$data[] = $address;
		}
	}
	return implode(' ',$data);
};

function sanitize_email_in_html( $content ) {
	$pattern = '/[a-z0-9_\-\+\.]+@[a-z0-9\-]+\.([a-z]{2,3})?(\.[a-z]{2})?/i';

	// preg_match_all returns an associative array
	preg_match_all($pattern, $content, $matches);
	
	foreach ( $matches[0] as $address) {
		$email = filter_var($address,FILTER_VALIDATE_EMAIL);
		if ( $email ) {
			$email = preg_replace('/\./', '[dot]', $email);
			$email = preg_replace('/\@/', '[at]', $email);
			$content = str_replace($address,$email,$content);
		}
	}
	return $content;	
};

echo sanitize_email('Hello Sir dinesh.shardiwal@gmail.com are you. your email is rakesh.shardiwal@gmail.com');

Output 

Hello Sir dinesh[dot]shardiwal[at]gmail[dot]com are you. your email is rakesh[dot]shardiwal[at]gmail[dot]com