- substr: documentation ( source)
<?php
$agent_name = 'aperry@clickspark.com';
$agent_name2 = 'crobinson';
$agent_name = substr($agent_name, 0, indexof('@', $agent_name));
$agent_name2 = substr($agent_name2, 0, indexof('@', $agent_name2));
echo $agent_name.PHP_EOL.$agent_name2;