$re = '/\s*(?:"([^"]*)"|([^,""<>]*))?\s*(?:(?:,|<|\s+|^)([^<@\s,]+@[^>@\s,]+)>?)\s*/m';
$str = 'Test1 <test1@x.com>, Test Two test2@x.y.com,T e s t 3 <test3@z.com>, Test@4 <test4@abc.com>, test5@cde.com,
"Bob Smith" <bob@company.com>, joe@company.com, "John Doe"<john@company.com>, Billy Doe<billy@company.com>
';
preg_match_all($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