[1] =>
user1@domain.co.uk
user1@domain.co.uk
user1@domain.co.uk
user1@domain.co.uk
user1@domain.co.uk
user1@domain.co.uk
 [10] =>
user1@domain.co.uk
user1@domain.co.uk
user1@domain.co.uk


$list_of_email_address_from_domains = explode("\n", $list_of_email_address_from_domains);
echo "list2:";
print_r($list_of_email_address_from_domains);

list2:Array
(
    [0] => Array
)