After changing ISPs the former email account was removed, but our iPad still tries to log into it. The server reports that the password is incorrect, which is odd. As a result, in Mail it wants me to re-enter the password before it will let me change any settings.

I do not want to remove this account because it has years of archived emails. I simply want to turn it off. But all of those controls are greyed out. Can anyone offer a suggestion on how to do this?