public async Task <IActionResult> ApproveClient(string id)
        {
            try
            {
                if (string.IsNullOrEmpty(id))
                {
                    throw new DBConcurrencyException();
                }

                var user = await _userHelper.GetUserByIdAsync(id);

                if (user == null)
                {
                    throw new DBConcurrencyException();
                }

                user.IsApproved          = true;
                user.AccountApprovedDate = DateTime.Now;

                var result = await _userHelper.UpdateUserAsync(user);

                if (!result.Succeeded)
                {
                    throw new DBConcurrencyException();
                }

                _mailHelper.SendApproveClient(user.Email, user.Name, user.GuidId);

                await _notificationRepository.DeleteAsync(await _notificationRepository.GetByGuidIdAsync(user.GuidId));

                return(RedirectToAction(nameof(ListUsers)));
            }
            catch (DBConcurrencyException)
            {
                return(new NotFoundViewResult("_Error404"));
            }
            catch (Exception)
            {
                return(new NotFoundViewResult("_Error500"));
            }
        }