so I'm interested in adding a newsletter subscription to my website for visitors that are interested. I configured the cgi script, now I'm only wondering how to use the smtp feature with astahost.. would 'localhost' suffice, or will I be needing to get smtp auth? thanks for the help

Probably setup an email account in your Cpanel and use that as your login, or you can just try localhost first to see if it can send some mails. As I see you aren't hosted, get hosted and see what the Cpanel has to offer you and help you do most things you want to your hosting account!