Vandermolen, just a note, not just to you who may not wish to do so, but to anyone who gets their inbox in a jam. You can always go back and do a bit of housecleaning on some items which you saved for no particular reason, and once you get their number under control, your inbox becomes a viable entity again. That was one of the travails of being a non-subscriber, but can be useful for subscribers too. Even with great space, I still go back and take a broom to mine on occasion... 

Thanks Gurn.
I'm aware of this option, however, my 'Silver Subscriber status suggests that I should have a capacity of 1000 messages but my box stopped functioning after about 300 and I am no longer designated as a subscriber at all, although the monthly payment is still apparently going out of my bank account.