Here is exactly what information is collected when you create an account and play on this server.
When you register in-game, your account profile stores your IP address and the email address you typed into the game client. I literally do not have a choice in this, it is automatically stored straight into the server database.
Because it is logged there, this data is visible to me as the server owner. However! I will change all IP addresses inside of the database to 127.0.0.1, which is a dummy address that points to the device accessing it. The same thing with emails, any email entered will be changed to a@gmail.com
If you ever need to perform account actions like changing details, make sure to use the Server Tools panel directly.