cyrus accepts mails for "unknown users"

Hi,

I've seen that simular questions have been discussed here, but I'm not sure if 
this problem is the same (sorry if yes and I just didn't get it):

I'm runnung sendmail 8.12.3 with cyrusv2 local mailer (Debian woody standard 
package) and cyrus 2.1.17 (backport from http://people.debian.org/~hmh/). 
Today I had a heavy spam attack caused by the fact, that sendmail accepts 
mails for non existing users. EMails to unknown accounts on local domains 
(local-host-names) will be accepted and than bounced. Is there a way to 
stop/reject these mails at "rcpt to: user unknown"-point?

Thanks,
Marcus

--

-- 

You know, some of these stories are pretty good.  I never knew mice
lived such interesting lives.

  -- Homer Simpson
     Itchy & Scratchy & Marge
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