public async Task <IActionResult> RegisterNewLetter([FromBody] EmailRegisterModel emailRegisterModel)
        {
            if (_newsLetterRepository.IsEmailRegistered(emailRegisterModel.Email))
            {
                return(StatusCode(AppStatusCode.EmailRegistered));
            }

            var result = await _newsLetterRepository.RegisterSubscriptionEmail(emailRegisterModel.Email);

            if (!result)
            {
                return(BadRequest());
            }

            return(Ok());
        }