Thanks for the reply, to answer your question:
-yes, i have checked everything, cc, bcc, to: field, everything. There is absolutely no way that these messages where forwarded on either.
I have even checked in the account online, because it is a pop/smtp server. the person they are being sent to is not even in the online adress book.
It really makes absolutely no sense to me. Is there a way to clear all the info stored on the mail database without loosing all the messages "on my mac" in mailboxes?