Email "This account already exists"

Hi...I transferred all my files from an old iMac to a newer one yesterday. My one email account can't seem to connect to my internet service provider, which my main email. It shows my correct email but it keeps asking for my password. When I enter the password it say's "This account already exists". I also went to System Preferences>Internet Accounts and the password field is always empty. When I attempt to enter the password I get the same error box. I have attached a few screenshots of what I am seeing...Thanks