Question email to be downgraded

i am in england and on bt , i sometimes check emails on my server instead of thunderbird because the server sometimes holds back what it thinks is spam.
i looked today and it said my email is due to be downgraded ????
The help desk said they could not access my account , does anyone know what the downgraded message means
 
my email provider is bt I phoned them but the person I spoke to did not know the answer.
some threads say it happens if you don't use the email server for 180 days , I do.
some say its because my email ends in @btopenworld.com and not internet.com or mail.com ???