Do you send to multiple email segments or on different days, and want to get better stats on what is performing? If so, you need to start tagging your links with campaign parameters in Google Analytics.
Adding custom campaign parameters to your links will allow you to track the effectiveness of your marketing. The parameters allow you to pull in all sorts of data, not just a referral. This is especially important with email analytics. Traffic from emails is extremely hard to find in Google Analytics if you are not tagging the emails with a campaign.