title: Encode non ascii characters in C# .NET
body: <p>I want to add a custom header to the emails my application is sending out. The header name can only contain ASCII chars, but for the value and users could potentially enter UTF-8 characters and I have to base64-encode them. Also I have to decode them back to UTF-8 to show them back to the user in the UI.</p>
  
  <p>What's the best way to do this?</p>