stripped down function to get emails from text files. Source: squirrelmail-webmail-1.4.22 functions/url_parser.php

gistfile1.php

<?php

function parse_emails ($text) {
 
 	$IP_RegExp_Match = '\\[?[0-9]{1,3}(\\.[0-9]{1,3}){3}\\]?';
	$Host_RegExp_Match = '(' . $IP_RegExp_Match . '|[0-9a-z]([-.]?[0-9a-z])*\\.[a-z][a-z]+)';
	$Email_RegExp_Match = '[0-9a-z]([-_.+]?[0-9a-z])*(%' . $Host_RegExp_Match . ')?@' . $Host_RegExp_Match;
	 	 
	preg_match_all('/'.$Email_RegExp_Match.'/i', $text, $regs);

	$addresses = array_merge(array_unique($regs[0]));
	 
	return $addresses;
}