Loads of incoming email to bogus email addresses with no from address

[Mail Administrator]

Hi all,

Today my mail server - fedora/sendmail/mailscanner/sa/mailwatch has approx
3000 non legitimate emails to one of the domains I scan and relay to
Exchange 2003. All these emails have no from address and the subject
varies from a)**Message you sent blocked by our bulk email filter** and
b)Mail System Error - Returned Mail

Is there a way to stop this?

I scan and fwd mails for many domain.
Maybe there is a way that somewhere I can set - these are the only email
addresses I want to accept email for , for a particulare domain, and drop
all other email. Then MS Can only receive genuine email addresses? This
maybe is not the best solution as if the exchange admin adds new accounts
he would have to notify us of the new addresses...

Any help or pointers would be greatly received

Regards
Kevin

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