To access your Iowa-Host control panel, you'll need to log in to your Iowa-Host Account Portal.
Once you are logged in, go to the top left box that says "Your Active Products/Services" and click on "View All".
On the next screen, click on the green "Active" button for the particular domain's control panel that you want to login to and it'll take you to the shortcuts for that domain.
Once you're on the screen with more options, you'll see a list, on the left side of the page, where you'll have options that allow you to go to control panel, webmail, or allow you to change your password.
