That's not the point. The point is NO ONE can promise 100% uptime. One can promise a 99.999% uptime and refund for the downtime. If one promises 100% uptime, either he's lying or he's just stupid.
I don't know the details of the email SLA, but for infrastructure: power, networking etc. on our hosted Rackspace servers, we have a 100% SLA. And it's not a lame prorated thing: they pay 5% of the monthly cost back for 30 hours of downtime.
So 99% power/network uptime in a month would cost them 70% of what we pay per month.
An SLA isn't about promising what they will deliver, not really, it's about what they will deliver if they want to keep 100% of the customer's payments.
