Well, your forum settings can jsut use the default socket (in linux/unix) as it doesn't need a valid smtp server to send mail.
though if you do choose to use SMTP to send mail, you have to authenticate to the smtp server (it own't just let you send mail without authenticating to an account); I'm not sure where you'd enter the authentication information, I think it's in one of the files in the libs directory (never used an SMTP server with the UBB)
