The code attached takes an array of emails and makes them all lower case. I would also like to validate these emails. How do I change the script below to not only turn them to lower case, but also check if they don't have any characters like "'" or any other stuff that wouldn't be in an email?
// NORMALIZE TO LOWER CASE BECAUSE email@example.com == You@YOUR.OrG IN EMAIL
$existing_emails = trim(strtolower($row["email_cre"]));