How to test ForgotPassword in unit testing

I am trying to test the ForgotPassword method of my Account Controller, and I need to know if it sends a mail or not. I don't mind using a sort of mock for the email service, but i don't know how to implement it. I'm a bit new in ASP.NET and Unit Testing.

Here's my test method

[TestMethod]
public void ForgotPassword_ExistentUser()
{
    var sut = new AccountController(_applicationUserManager, _appSignInManager, _authenticationManagerMock, _context, _iregisterMock, _iCategoriesMock, _iProvincesMock);

    CreateApplicationUserWithRole("User");

    var forgotPasswordModel = new ForgotPasswordViewModel()
    {
        Email = "test@test.com"
    };
    var result = sut.ForgotPassword(forgotPasswordModel).Result;

    Assert.IsInstanceOfType(result, typeof(ViewResult));
    var viewResult = (ViewResult)result;
    Assert.AreEqual("ForgotPasswordConfirmation", viewResult.ViewName);
}

And my ForgotPassword Post method

[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public async Task<ActionResult> ForgotPassword(ForgotPasswordViewModel model)
{
    if (ModelState.IsValid)
    {
        var user = await _userManager.FindByNameAsync(model.Email);
        if (user == null || !(await _userManager.IsEmailConfirmedAsync(user.Id)))
        {
            TempData["message"] = "The email is not confirmed or the user has not been created yet";
            return View(model);
        }

        // Send an email with this link
        string code = await _userManager.GeneratePasswordResetTokenAsync(user.Id);
        var callbackUrl = Url.Action("ResetPassword", "Account", new { userId = user.Id, code = code }, protocol: Request.Url.Scheme);
        var message = new IdentityMessage();
        message.Body = "Please reset your password by clicking <a href=\"" + callbackUrl + "\">here</a>";
        message.Subject = "Reset Password";
        message.Destination = user.Email;
        await _userManager.EmailService.SendAsync(message);
        return RedirectToAction("ForgotPasswordConfirmation", "Account");
    }

    TempData["message"] = "There was a problem with the email";
    return View(model);
}