user preferences and mail relays

[Michael Grant]

Yesterday I posed the question about the mail relays and
spamass-milter.  I did some more thinking about this last night.  I
need some clearification on some things.

In version 0.2.0, the man page for the -u option states:

     -u defaultuser
             Pass the username part of the first recipient to spamc with the
             -u flag.  This allows user preferences files to be used.  If the
             message is addressed to multiple recipients, the username
             defaultuser is passed instead.

             Note that spamass-milter does not know whether an email is incom-
             ing or outgoing, so a message from <address@hidden> to
             <address@hidden> will make spamass-milter pass -u user2 to
             spamc.

If I use the -u flag, is that the user that is passed when
spamass-milter cannot figure out a user to use from the headers?

There is a file in /etc/mail/local-host-names which contains the names
of all the domains that my box are known as.  Couldn't spamass-milter
be smart enough to read this file and then it would know which domain
was localdomain.com and then it could know to pass user1 instead of
user2 to spamc?

In this case, the -u option could be used for mail where
spamass-milter can't figure out the username.

The one major problem I see is how can spamass-milter figure out the
user to pass to spamc if the user it gets from address@hidden is an alias
(i.e. it's not a username on the system).  I don't think it can know. 
In this case, it's going to be better to use procmail at the user
level when the message is delivered rather than at the milter level.

Michael Grant