RSS Feeds are a great way to have your website readers stay up to date on site content. It’s less intrusive to the reader compared to email newsletters, and feeds allow users to read fresh content at their discretion and at their convenience.
But one con to using RSS only is that you never know how many people have subscribed. You also never know when readers unsubscribe from your feed. So in this aspect, newsletters are the winner, since you can tell when people subscribe or unsubscribe.
So when considering whether to have your readers rely only on RSS, only on newsletters, or both, be sure to consider how important it is that you know who’s even listening.