Regarding spam

[jason dictos]

Hi All,

   I run my own mailsever, and I just wanna know its possible for someone to 
send an email to my mail box, but yet have no one specified in the TO or CC 
fields. I guess those fields are probably optional, but how can I adjust my 
mailserver to reject messages sent to someones mailbox without their name 
being in the TO or CC fields?

P.S. My mailserver is a CLOSED relay.

Thanks,
-Jason