SendMail issue

Hi all, Im using the java api to send mails
to a list of users of my site.
The problem is that I get tons of "Mail Delivery Subsystem - User Unknow " mails
that overflow my inbox and after a while make my program die...
Does anyone know how can I configure, send mail or my perssonal account in order to avoid these
returned mails ?
Can I put a filter or something just to count the returned mail and delete it ;P
I've search in the sendmail.org site but.....
I think javaranch has a better comunity

Thanks for the answers...