<p><a href="@Model.Url" class="button">ACTIVATE MY ACCOUNT</a></p>

[Authorize]
public class AccountController : BaseController
{

    // GET: /Account/ConfirmEmail
    [AllowAnonymous]
    public async Task<ActionResult> ConfirmEmail(string code, string userId)
    {
        if (code == null || userId == null)
        {
            return View("Error");
        }

    // Rest of the code... not relevant to the question
}