Here are the steps:

1) downloaded the latest tomcat bundled Magnolia from sourceforge (rc3)
2) started up using Sun JDK 1.5.0_07
3) configured smtp server
4) opened sample mail form and configured form properties
5) filled out form and submitted

At this point I received the e-mail from Magnolia just fine but the page in the browser maintains the mail form's url (http://localhost:8080/magnoliaAuthor/mailform.html) and the HTTP redirect is never sent from the server. I double checked to ensure that it was pointing to a valid page for the redirect. I've also tried this in both Firefox and IE.

I've also tried this off of the latest code from the trunk and I get the same problem. When I step through the code the problem seems to be a flag called include that gets set in the ApplicationHttpResponse object in tomcat to true. I don't understand tomcat internals enough to know what's going on so that's where I stopped. I did try this on my own jsp template where I put a redirect in and it never sends the redirect (same reason). I'm assuming that it isn't a tomcat issue though.