kgagne on "Category links in RSS-driven MailChimp campaign"

I am using MailChimp to generate email newsletters from my RSS feed. At the bottom of each newsletter are the post's tags and categories. In this example, clicking on the tag "portal" goes here:

http://www.thepubcast.org/?taxonomy=post_tag&term=portal

which resolves to this:

http://www.thepubcast.org/tag/portal/

But clicking on the category "pubcast" goes here:

http://www.thepubcast.org/?taxonomy=category&term=pubcast

However, "Pubcast" is only the category's name; its slug is "podcast". So the above URL presents a 404, instead of resolving here:

http://www.thepubcast.org/category/podcast/

Is this a problem with WordPress and its RSS feed, or with MailChimp?

-Ken