Rule suggestion - smtp sanity

[arni]

From large providers i sometimes recieve messages through encrypted 
smtp, the header looks smth like this (qmail):

...  with (AES256-SHA encrypted) SMTP; ...

Would it be a good idea to give a minimal negative score on this -0.1 or 
-0.2 if this happens on the last hop? - It proves that the sending smtp 
server is very protocol sane, which spambots are usually not.

arni