This is a security feature to stop outside users from spamming from our server.
Most programs attempt to send email before getting email off of the server.
If you immediately try and send the email again after getting your email off the server the port will allow you send permissions to our server. There is a time limit to close the mail port so it must done immediately. There are three likely reasons for this to occur. Your user name and password are not correct. Your Internet Service Provider may be blocking the required connection ports.