$re = '/\"(?<caller>[a-zA-Z0-9_\-\.]+@[a-zA-Z0-9_\-\.]+\.[a-zA-Z]{2,5})\",\"(?<receiver>[a-zA-Z0-9_\-\.]+@[a-zA-Z0-9_\-\.]+\.[a-zA-Z]{2,5})\"/m';
$str = ' ....."","10/30/2018 7:31:08 AM","10/30/2018 7:41:52 AM","natalie.someone@email.com","andrew.someone@email.com","UCCAPI/3823.323.10827.* OC/16.0.10827.20150 (Skype for Business)","UCCAPI/16.0.10730.2342342 OC/16.0.10730.20088 (Skype for Business)","","","","****-5042-5F76-A879-***7","","","","","200","[IM]","{""RequestType"":""BYE"",""RequestTime"":""2018-10-30T07:41:52.2147589"",""ContentType"":"""",""ResponseCode"":""200"",..';
preg_match_all($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