How to manage email which is coming to the catch-all address

[#1]

Hi,
I usually create a new email address for each new shop that I buy something online from, (e.g. onlineshop11@mydomain.force9.co.uk) then pick that mail up from the catch-all mailbox. I then know that email's origin.
Now I am receiving Spam sent to one of these addresses. I've had a look around in the email settings but can't see where I can block mail that's going to an address, only from an email address or domain.
Can I fix this without setting up a new mailbox for that address?
Thanks in advance,
Steve

[#2]

To block all mail to a particular 'to' address, I think you need to redirect it to 'blackhole'. I don't think the redirect name has to exist as a mailbox before you can do this.
Select the 'Redirect' tab in Manage My Mail and click 'Add New Redirect'. Then enter the 'to' address you want to block and select the 'I would like to blackhole this address…' radio button.
Click 'Add' and within 30 minutes the redirect should take effect.
David

[#3]

Thanks for your help. 
I'll give it a go.
Steve

[#4]

Yes, that's just what I needed. Its working fine, thanks a lot.

Steve