With the new notification method about posts on Warm Showers, you get a nice looking email. The title of the article is a link to the actual article on the Warmshowers.org site. If you want to respond to someone (perhaps they've asked a question, or looking for partners for a ride), just click on the title in the email - that will take you to the warmshowers site, where you can respond. Responding to the email won't work, since the email is just a notification about a posting on the site.