Configure sendmail to reject mail for unknown users?

[Les Mikesell]

On Tue, 2006-03-14 at 12:01, Timothy Alberts wrote:

> > are you sure there isn't an MX-record/host for the domain in question?
> > if it's "msiscales.com" there are two - so in that case, by the time
> > the mail reaches your internal mail server it's too late (you're
> > dealing with post-acceptance bounces, not bounces on delivery).
> 
> Yes, it is 'msiscales.com'. The second MX record is supposed to be a
> backup when our server is down.  The mail should be coming to us first,
> I think that's reflected by the priority within the DNS MX record.
> Which as you say, when our server goes down, all mail goes through our
> backup and we get bombarded with the spam and there's nothing I can do
> but try and filter it.  Under normal circumstances, all mail should come
> to the main server in question where I want it to be rejected.

These days a lot of spam is sent to the highest valued MX record
instead of the preferred one specifically to avoid spam filtering.
There is really not a lot of value in having a backup MX because
the sending relays will queue for you anyway, but if you do have
one you should run the same filtering as your primary system.

-- 
  Les Mikesell
   lesmikesell at gmail.com