[toaster] Secondary MX Question

[Peter Maag]

   To The List,
I have been trying to find a solution to this problem for quite some 
time, didn't find it so I thought I would ask you fine folks.  
Currently, in DNS(djbdns) I use the following entries for MX records:
        
            @domain.com::scanner.domain.com:1
            @domain.com::popserver.domain.com:1000

The MX record with "1" priority is setup to scan incoming mail for 
viruses, etc and then smtproute it over to the main POP server where 
users check their mail.

The problem occurs in that some of the mail(33% ish) will bypass the 
scanner server and will be sent directly to the primary POP server 
unscanned.  I can verify that both machines are online when this happens.

So, are those the correct settings for the system I am creating, or will 
this always be the case.  I would like no mail to be delivered to the 
primary POP server directly, unless the scanner server is down/offline.

Any takers?  Thanks in advance for the support.

   Peter