There are a few solutions to this:
- Switch to Newspaper: If you select the Newspaper option, then you will only receive one email per day, containing all stories from the last 24 hours.
- Filter your feeds: To do that, edit a feed (for example by clicking on the edit-link next to the feeds’ title in the emails you receive) and set a keyword, tag, or author filter. Then you will receive less messages going forward. You can simulate on the filter screen which (and how many) messages you would have received in the past with those selections.
- Follow less feeds ;)
Also make sure that you are following the feeds with the “Headlines only”-option, as otherwise the emails may contain too much content.