We could certainly operate more cheaply if we didn't have every email replicated to another server (and a third in a second datacentre) as well as backed up dai

We could certainly operate more cheaply if we didn't have every email replicated to another server (and a third in a second datacentre) as well as backed up daily to yet another machine with a different operating system and different security model. You're right, doing it properly costs money, and I'm really glad there are enough people willing to pay for good email that FastMail has a viable business model. We've never made stupid-money like the tumblrs or instagrams of the world, but we're growing reliably and at a pace where our infrastructure can be improved gradually. And we didn't sell for heaps of money either, but then we've been able to keep on operating much the same as before (apart from me getting a 2 year stint in Oslo to do skills and knowledge exchange with related teams inside Opera)