How to track email and off-line traffic to your website
Google Analytics can only track activity from the browser. Any off-line campaigns will naturally be tracked as ‘direct traffic’, and email campaigns will be tracked as a referral from an on-line email interface such as Gmail, or Hotmail, or as direct traffic if the user follows a link from a desktop tool like Outlook.
You can change this by tagging your links. This adds some information on to the end of the website address, and it feeds into Google Analytics – overriding what would be tracked as direct or an incorrect referral.