Spam with Trend Micro CSM and No recipient specified

We continue to chase a problem of mail in our failed mail folder on SBS2003.
We are using Trend Micro's CSM as the front line for spam control. The
connections are using POP3, we are unable to set up a SMTP service.
Everything is the latest versions with all patches and updates installed.

The mail that is accumulating in the failed mail folder is clearly spam. It
comes in without any specified TO address so exchange does its thing and
fails the mail.

I've tried the settings in SMTP to dump the "no addressee" but that
apparently doesn't apply to POP3. I've tried rules in the eManager for
ScanMail but it apparently isn't smart enough to catch mail without a
specified recipient. Per Trend's suggestion, we have tried rules to block
mail to "undisclosed-recipient" and also "unspecified-recipient" but they
don't catch it.

Does anyone else experience this and have you found a way to stop it?

I did see a comment one time that apparently a favored trick is to send the
spam as a BCC, the address gets dropped and gets by the walls that way.
Surely there is a way to stop this without just resigning from the internet?

Any ideas would be appreciated. I am getting about 15-25 failed mails per
day, all appear to be the similar thing. No TO addressee is specified and
the body of the message doesn't have anything in it.

Thanks

Paul P