Ask HN: How do you manage prepaid recurring payments for your clients?

Hi, I just left FastMail for RackSpace & as far as I can tell, the services I'm to get once I complete the transition will be sufficient. But there's one thing I'll no longer have at RackSpace that I liked having at FastMail: 'Account Pools'. At FastMail, I was able to deposit funds into an Account Pool, such that there would be years worth of untouchable funds there which would automatically be used to cover annual fees. Being that Gandi allowed domain registration to be prepaid for 10 years at a time, I figured I could deposit 10 years worth of email service fees into the FastMail pool, & let the whole thing be hands-free. I hadn't sorted how to handle hosting yet though. But I imagine it wouldn't be too hard to find someone to let me prepay such that a 'set-it-and-forget-it' 10 year plan could be something I could sell that's easy to setup. RackSpace doesn't allow prepayments of any kind. Just a single credit card to ce charged periodically. I haven't looked yet, but will be in the market for some kind of QuickBooks add-on app, or WordPress ecommerce plugin to allow per-client 'pre-paid account' management somehow. I'd be interested in hearing how fellow HN'ers handle similar situations.