Yahoo continued its efforts to push RSS across as many of its products as possible tonight, flipping the switch on an RSS reader as part of the beta version of its new Yahoo Mail. This one was a no-brainer. The email environment is a logical place to consume RSS feeds; there are already plug-ins for Outlook, for example. What’s more, the new Yahoo Mail evolved out of Oddpost, and RSS was one of the distinguishing features of that email service.

For those who don’t have access to the new Yahoo Mail (it’s still a closed beta), it works like this. The feeds appear in the left column in a folder-like structure. You can view each feed indvidually, or a “feed of feeds,” which aggregates all your feed items together in chronological order. (Click the screen grab to see more. Notice also the integration with Yahoo 360 and MyWeb.) Ethan Diamond, director of product development for Yahoo Mail, likens it to a “river of news” concept, where the latest items from all your feeds flow in, one on top of another.

At the start, Yahoo will populate feed lists with a selection of top RSS feeds, or it will automatically import your MyYahoo subscriptions, if you have any.

The feed content will appear as full-text, or whatever preference is built into the feed. As with the rest of Yahoo Mail, everything is drag-and-drop. And you can archive particular entries into a folder and email items to others.

Out of the gate, this may not be the aggregator of choice for power users. You can’t group feeds into folders yet. And there is no OPML importing. Yahoo is aiming this at the average non-RSS-savvy Yahoo user for now. But those features will come. “The basics for the vast majority of email users will suffice,” Diamond told us.

But, Yahoo’s Scott Gatz is quick to add, “I don’t want to knock the application we have. I’ve been using it for a month or so now. It’s a powerful RSS reader.”

Also, RSS-related: The popular “Add to MyYahoo” button, which web site owners used to help their users subscribe to feeds, is giving way to a “Add to Yahoo” button. That will allow users to add their subscriptions to any of the Yahoo services that aggregate feeds.

John Furrier has the PodTech podcast about this here.