pop threshold reached tor the user... Change the POP settings to delete messages from the server and Renable the account to fetch messages

pop threshold reached tor the user... Change the POP settings to delete messages from the server and Renable the account to fetch messages

Getting this message ...did go on to dasboard and tried to set Expunge etc but although it says successful it makes no difference.
Also tried to upgrade but not working  either
Anyone else go same problem...and answer?
How do I re enable to fetch messages????