Building on mandaleeka’s answer, break the string up using a space delimeter then use filter_var to sanitize then validate to see if what remains is a legitimate email address:
function extract_email_address ($string) {
foreach(preg_split('/\s/', $string) as $token) {
$email = filter_var(filter_var($token, FILTER_SANITIZE_EMAIL), FILTER_VALIDATE_EMAIL);
if ($email !== false) {
$emails[] = $email;
}
}
return $emails;
}