MailScanner - different file rules for inbound and outbound mail

I have a Mailscanner/Sendmail/Spamassasin solution in place and it's working well. I use this to filter inbound mail, outbound mail is handled by our internal
mail server.
I want to change this so that the M/S/S server handles all inbound and outbound mail but i need to have a different rule set of allowable outbound mail. As an example
we do not allow various file types inbound but at times we do need to send them out.
Can i have different rules for inbound/outbound mail?

Thanks.

S.