public async void SendNotification(string from, string to, string subject, string body, bool isHtml, CancellationToken cancellationToken) 
        {
            var mail = new Mail();
            mail.FromAddress = new MailAddress(from);
            mail.ToAddress.Add(new MailAddress(to));  // TESTING
            mail.Subject = subject;
            mail.Body = new MailBody() { Body = body, IsHtml = isHtml };
            await _mailClient.SendMailAsync(mail);
        }