I did a search and didn't see this had been suggested before, so here goes.
I'd like to see an additional checkbox on the External POP Servers page that would allow checking of a particular external POP server to be turned on/off.
The purpose is to temporarily disable a particular POP server/account from being checked without having to "Delete" it, and subsequently re-enter the server/username/password/options to re-add it later.
The benefit is to those of us who use a POP3 client "most" of the time, but find ourselves on the road to locations where access to various mail services (Yahoo, MSN, etc.) is blocked for various reasons, or where our typical POP3 client configuration isn't available and we're limited to webmail only.
It would also have the effect of reducing bandwidth/storage for the SpamCop mail server during those times when checking the external accounts wasn't necessary.
Just a thought, for whatever it may be worth.