Previewing emails with addresses with names

If you have something like this in your [header](http://aboutcode.net/postal/email-headers.html):
`To: John Smith `

And want to preview the email using the [preview feature](http://aboutcode.net/postal/email-headers.html).

```
public class PreviewConroller : Controller
{
public ActionResult Example()
{
dynamic email = new Email("Example");
// set up the email ...

return new EmailViewResult(email);
}
}
```

Then you'll get this error: `An invalid character was found in the mail header: '<'`

I believe it's related to #108