You are receiving this e-mail message because you are an administrator of the following SharePoint Web site, which has exceeded the warning level for storage

If you are the site collection admin and if you received this email "You are receiving this e-mail message because you are an administrator of the following SharePoint Web site, which has exceeded the warning level for storage..." No need to Panic. :)

You received this email because the site collection quota is nearing your total storage.
 
Steps.
  1. Go to Central Administration
  2. Navigate to Sitecollections
  3. Click on Configure Quota and locks
  4. Change the storage size
 
Happy Share Pointing :-)