how to not run SA-scan if on whitelist/blacklist

[Ramprasad]

We are using MS 4.50.15  for spamassassin and AV checks 

I use 
"Is Definitely Not Spam  = "  feature for whitelisting 
when a mail is already on this how do I tell MS not to run SA for such a
mail. Currently the mail is sent thru spamassassin and the checks happen
before the whitelisting happens 

Thanks
Ram