rule checking environment variable

[Miguel Angel <sk...@gmail.com>]

Hello,
     i am using spamassassin 3.2.3 with qmail and simscan, the problem i have it is that my authenticated smtp 
users have any mails rejected because a high score, i know i can use other ip not listed in mx of the domains 
to create a server with required authentication where i should not scan for spam (and make my users send with 
that) but i would like to search other solution, i would like to create a spamassassin rule with a -100 score 
that search for an environment variable but i have not found anything about that in the 
page|wiki|mailing-list, it is that possible to do? when qmail authenticate the users adds the variable 
SMTP_AUTH_USER so when spamc it is launched from simscan this variable should be there yet. I am using now 
whitelist_from *@domains.com but it is not a good idea because many spammers change the "From" address domain 
to be the same of the rcpto.

Best Regards,
Miguel Angel.