A screenshot of the upcoming iCloud storage service from Apple shows that if your free 5GB of storage gets eaten up by backups, calendars, or other data, your e-mail will get choked out, as noted by a screenshot sent to MacRumors. If the storage cap is reached, users stop receiving e-mail at their me.com addresses, and anything sent there is bounced back to the sender.

On the one hand, this isn't terribly surprising—what should Apple do, let people keep using space they're not supposed to have? But because e-mail is being routed through the same virtual space that can only hold a fraction of a full-sized iPhone backup, this is bound to happen quite a bit.

It's not only e-mail that stops, either: device backups will also cease until space is cleared. Apple hasn't announced anything to this effect yet, but we expect that there will be pricing tiers above the free 5GB for customers with a larger, more active setup of devices.

Another possible solution would be to route e-mail outside the 5GB box, similar to the PhotoStream service. As long as Apple keeps an e-mail size cap, that shouldn't be too much of a traffic hit. In fact, given a choice of exempt services, we'd almost certainly choose e-mail over photos.