Does the catchall work?

I'm trying to completely remove all e-mails that are not addressed to a valid local user. I get a whole lot of spam to my domain, and as it is configured now - all emails are bounced back to spammer.

I have added a catchall of /dev/null in vexim, and exim main log looks like this:
2009-06-25 07:31:23 1MJhYN-0006Ct-DH => /dev/null <blah@domain.com> R=virtual_domains_catchall T=**bypassed**

When I send mail to domain I don't get a bounce. Does that mean that my solution worked?