You can have the community send you email when content you care about is added or changed. This is an alternative to feeds, which require a feed aggregator (although you can use both feeds and email notifications, of course). Because an email is sent for each notification you request, you might prefer subscribing to feeds if you'd rather not get all the email.
To begin receiving email notifications, navigate to the area you care about — a space or document or blog, for example — and click Receive email notifications under Actions. To stop receiving email notifications, click Stop email notifications instead.