[Exim] No spam check for internal hosts

Hi Guys,

i'm using exim 4.24 with exiscan path and spamassassin with this conf:

warn  message = X-Spam-Score: $spam_score ($spam_bar)
       spam = nobody:true
warn  message = X-Spam-Report: $spam_report
       spam = nobody:true
warn  message = X-Redirect-To: spam@???
       spam = nobody

  # Add X-Spam-Flag if spam is over system-wide threshold
  warn message = X-Spam-Flag: YES
       spam = nobody

Now i would like to avoid spam checking for my internal hosts (10.0.0.0/16).... i've set in spamassassin local.cf
whitelist_from and trusted_networks 10. but without luck.
Maybe if i avoid to call spamd process at all checking source ip address....can i set hosts = !10.0.0.0/16 in configuration above?

Thanks for your attention

Rick