Re: [cobalt-users] Mailscanner not getting viruses all the time

[Kim Schulz <kim@xxxxxxxxx>]

[snip]
> How does the Internet know to deliver mail to the primary MX server?
> By what mechanism does the primary MX forward the mails onto secondary
> MX? Are you using RBL's at all as part of your primary MX server
> Sendmail config or through the MailScanner config?


well mailservices normally use the primary MX (Highest Priority). The
forwarding is handled by sendmail via normal mailertable settings
(esmtp). 
RBL's are handled by MailScanner, but we have a long list of rejects in
the sendmail access list (bacically alot of dynamic ip hostnames like
adsl domains).

 
> For example, if the Internet delivers your customer domain email with 
> primary MX set as the primary MX record in DNS and the secondary MX as
> a backup server, then it would be possible for the primary MX to
> reject the mail connection based on an RBL check but the sending
> server doesn't give up. It then tries to deliver to the next priority
> MX server listed by DNS. In your example this would mean the secondary
> MX then I presume it would miss out the virus checks.


You have a very good point there. I will check up on this right away. 
Do you know if it's possible to forward via sendmail's mailertable if
the secondary server isn't listed as an MX server? 


> I would also check whether your customer is really getting the virus
> mails or rather just the warning messages generated by MailScanner.


I have and it is both bounces from others mailscanners and viruses
itself. 



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