I got exactly this problem:

http://www.sendmail.org/virtual-hosting.html

Note 1: if you have a local user, say sam, and there is no key for sam@yourdomain.com and no catch-all key for @yourdomain.com, then sendmail will fall back to the local user sam when resolving sam@yourdomain.com. To prevent this, you must use either a catch-all key or an explicit key for sam@yourdomain.com; the error:nouser example above may be useful in this instance.



We got thousands of domains on this sendmail server where we use a 
virtusertable and local-host-names to add users/domains.

How do I stop spam coming to root@customerdomain.com ending in my local 
root mailbox for example. Adding root@customerdomain.com is not an option.
I wouldn't mind if the local mailboxes wouldn't work at all.


Thilo
--
Thilo Wunderlich

in comp.mail.misc i read:

>We got thousands of domains on this sendmail server where we use a 
>virtusertable and local-host-names to add users/domains.
>
>How do I stop spam coming to root@customerdomain.com ending in my local 
>root mailbox for example. Adding root@customerdomain.com is not an option.

make a catch-all that delivers to error:nouser, just as the note you quoted
specifies.

>I wouldn't mind if the local mailboxes wouldn't work at all.

you should.  but if you were a kook you might change the local mailer so
that it throws away messages.

i suggest comp.mail.sendmail for sendmail specific issues.

-- 
a signature

those who know me have no need of my name <not-a-real-address@usa.net> writes:
>make a catch-all that delivers to error:nouser, just as the note you quoted
>specifies.

But then the server would accept every wrong emailaddress, process it
and send it back then? This would produce a lot of load.
Or will it deny the reception at the 'front door' immediately just
the same way as it would do without?

Would this catch-all be for all hosted domains or just for the local server?

>>I wouldn't mind if the local mailboxes wouldn't work at all.

>you should.  but if you were a kook you might change the local mailer so
>that it throws away messages.

>i suggest comp.mail.sendmail for sendmail specific issues.

Oops, I wanted to post there. I'll try it there again.

Thanks for help
 Thilo
--
Thilo Wunderlich

[fu-t set]

in comp.mail.misc i read:
>those who know me have no need of my name <not-a-real-address@usa.net> writes:

>>make a catch-all that delivers to error:nouser, just as the note you quoted
>>specifies.
>
>But then the server would accept every wrong emailaddress, process it
>and send it back then? 

it would reject them during the smtp session.

>Would this catch-all be for all hosted domains or just for the local server?

one for each hosted domain.

-- 
a signature

On Sat, 31 Jan 2004, those who know me have no need of my name wrote:
> in comp.mail.misc i read:
>
> >We got thousands of domains on this sendmail server where we use a
> >virtusertable and local-host-names to add users/domains.
> >
> >How do I stop spam coming to root@customerdomain.com ending in my local
> >root mailbox for example. Adding root@customerdomain.com is not an option.
>
> make a catch-all that delivers to error:nouser, just as the note you quoted
> specifies.
>
> >I wouldn't mind if the local mailboxes wouldn't work at all.
>
> you should.  but if you were a kook you might change the local mailer so
> that it throws away messages.

Or DISALLOW the local mailer by OMITTING "mailer(local)" from your sendmail M4
configuration file (if that is acceptable to you).

> i suggest comp.mail.sendmail for sendmail specific issues.

I agree.