scanning on both primary and second MX servers

[Peter Russell]

It seems
> like I could solve this problem by making all our public MX
> records (both primary and secondary) MailScanner machines and
> having them both forward on to a third machine (which would run
> POP3/IMAP), but this is complicated, and we're a small company
> that probably can't easily spare another server-grade machine.
> Is there any other solution?  Should I just remove MailScanner
> from the backup MX and fall back to doing realtime blacklisting
> through sendmail's DNSBL feature?  That could work, but right
> now the policy is "always tag, never discard" spam, and I
> would have to delete spam if I had sendmail do that filtering.
> 
> Thanks for any advice anyone can offer.
> 
>   - Logan
We are a medium sized company and we run the 2 MailScanner MX machines 
that forward mail to exchange (and handle some virtual domains). It 
works great especially during upgrade times, i can simply shut MS down 
on either machine with out affecting mail flow.

With running 2 MS machines and having 2 sets of headers, you can handle 
this by changing the way the headers are added/appended in mailscanner.conf.

Your lower weight MX will usually get a huge percentage of spam, so why 
cant all mail from your backup MX be sent to your primary MX for 
scanning before delivery? You can ignore the headers from that machine, 
look in spam.assassin.conf