title: What is the best method for formatting email when using System.Net.Mail
body: <p>Hi I'm using <code>System.Net.Mail</code> to send some HTML formatted emails.</p>
  
  <p>What is the correct method for inserting css into the email message?</p>
  
  <p>I know I can apply formatting to each item, but I'ld rather use style sheets..</p>
  
  <p><strong>EDIT</strong>
  I should have mentioned that this is for an internal application, and I expect 99% of users to be using Outlook or other client, but never hotmail or gmail etc.</p>