How do skip HOLD for some messages in postfix header_checks

[ram]

I use MailScanner + postfix to do Antivirus scan on our servers 
So I use the header_checks to put messages in Hold for MailScanner to
pickup and scan

For some from-ids I do not want to put the mails on hold and send
without scan. These are high volume system alerts , and no scan is
required 

How do I achieve this ? 



Thanks
Ram


PS: I know this is more of a postfix query , but on the pf-list
He-who-shall-not-be-named would not like a Mailscanner question :-)