Question about virus/spam filtering for customers with mail servers

[Pat Lashley]

--On Monday, July 26, 2004 15:11:44 -0500 Richard Kuhns <rjk at wintek.com> wrote:

> I'm hoping someone will be willing to share a better way to handle this.
>
> We offer virus/spam filtering for customers with their own mail servers.
> We're currently implementing this by configuring the customer's firewall
> to only accept smtp connections from our servers (all running sendmail
> under FreeBSD 4), and the customer's MX records point to their server
> first and our server(s) second and third. In most cases this works just
> fine -- attempts by a mail server to deliver mail directly to the customer
> fail, the mail server tries the secondary MX site (us), we accept and
> filter the message and deliver it to the customer (or not).
>
> Sometimes, though, there's a very long delay for messages to be delivered
> - up to several days. In each case I've been able to track down, it's been
> a Microsoft Exchange 2000 server that has issues with sending messages to
> the secondary mail server.
>
> Does anyone have a good way we could use to list our server as the primary,
> and then forward the messages? I've been going through the bat book, but
> the indexing leaves a little to be desired and I haven't found anything
> that looks applicable yet.
>
> Any suggestions would be greatly appreciated. Thanks in advance...

If you're willing to abandon Sendmail, this sort of thing is trivial
with Exim.



-Pat