I don't think this will be exactly easy ... there are a couple of paths you could take. Just brainstorming ...
ASP programming: maybe modify the core email engine to override all TO addresses with yours?
I'm not slick enough to try that, so how about an IT approach? I might try something along the lines of setting up an email server on the local test server that accepts any email address and routes them all to one mailbox and point your host email server there. I
Or a DBA solution, write a stored procedure to set all the email addresses to your address? Put a trigger on the users table to run it?
I've been removing the email server from the test system to prevent annoying people at our site, but I understand you need those emails to go out! All of these are personal solutions, it wouldn't help the other testers, unfortunately.
Let us know if you come up with anything, it's an interesting question!
--
Roberta