$re = '/(?:<(?=[^<>]*>)|\[mailto:\s*(?=[^][]*]))([^\s@]+@[^\s@]+\.\w{2,})/m';
$str = 'Hello my Email Address is <foo.@hotmail.com> - Return foo@hotmail.com as Group1.
Hello my Email Address is [mailto: foo@hotmail.com] - Return foo@hotmail.com as Group2.
<foo.123@hotmail.com>, [mailto:foo$123@hotmail.com]';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php