The server has anti-spam software installed that won’t allow anyone to use the smtp server until they have logged in first. You need to login to your pop account and check your mail first. Wait 30 seconds before trying to send mail again for the server to recognize you after you check your mail. Once you have been authenticated you will be allowed to send mail for 30 minutes without having to login again. Your 30 minutes will start from the time you logged in last.