How to get email address from a long string

If you're not sure which part of the space-separated string is the e-mail address, you can split the string by spaces and use

filter_var($email, FILTER_VALIDATE_EMAIL)

on each substring.

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;
}