Normally, qmail-scanner only uses system-wide settings for every single mail 
when piping it through SpamAssassin.

This patch implements that qmail-scanner submits the recipient's address to 
spamc with the "-u" option, causing SpamAssassin to retrieve user-based 
settings. As the username is a mail address is that case (and not a system user 
name) you should either active vpopmail ("-v") or SQL support ("-q") to make
this usable.

Caution: There might be more than one RCPT TO header in an e-mail message. In 
that case this patch doesn't do anything, and qmail-scanner/SpamAssassin only 
uses the system-wide settings, as usual. I simply don't know which setting
would really make sense - SpamAssassin only accepts a single username on the
command line. Would it make sense to combine all settings from all users
(which might be even competing!), which would require a patch for SpamAssassin?
It seems like a lot of work to make qmail-scanner handle the same mail more
than once to catch the different user-based configurations.

Please let me know if you have any comments on that: mail@jonaspasche.de