Try increasing the Burst Time and decreasing the Burst size.
200 emails per 24 hours is your maximum, riding directly at the maximum is prone to failure. just try doing that with your car engine, keep the engine revs at the red line and watch the engine break down very quickly.
Instead throttle back to be bellow the maximum, try 175 or 150 emails every 26 hours.
Bear in mind that if you are using GoDaddy shared hosting, you are using a shared SMTP server.