Spammers circumvent MS

[Derrick Georgiades]

I have brought this up before, with no resolution.  Now spammers seem to be
catching on.
They are sending spam with multiple users from my domain in the To and CC
fields of the envelope.
The more local addresses they stuff in, the higher the chance they will hit
one that is whitelisted and then the whole email is whitelisted.
I know people have told me that because there is only one physical email for
many recipients that we can't block for some users and not others on the
same email.
My question is what can we do?  I have emails with a score over 10 SA points
to be deleted.  Is there a way to delete emails with a set score even if
that email hits a whitelisted address?
Any suggestions would be great.

Thanks
Derrick Georgiades