Avoid double scan

[Stefano Carlotto]

Is it possible to make a trusted MailScanner 'sign' email message in 
such a way that another MailScanner do not scan messages again?
I was thinking that in a situation with multiple mail server it may be 
useful in order to reduce global systems load. Of course the choice of 
not to scan messages should be based on the capacity to recognize the 
sign of the friendly server and on the time passed from the previous 
mailscanner scan.

thanks.