- Output for 5.6.0 - 5.6.23, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
<?php
$input = "john@gmail.co.uk";
preg_match('~@(.*?).~', $input, $output);
echo $output[1];