I've been using 30gigs.com email service for quite a while. I use it for non-sensitive / non-critical emails. At first, the interface was too clumsy. I don't know what kind of application they used, but it was cumbersome and took a long path to navigate.
Then, in the middle of operation, they changed the application, without notification. I think they are using horde right now. Now, I have to learn how to use the interface. It is still confusing. On top of that, some mails (actually a lot) are missing. Good thing I didn't store critical emails there, but I would assume that somebody must have done it.
Changing system in the middle of operation or services is not a good idea. It's a scary thing to do. They are too brave to do it. Cavalier? Or, maybe there is something serious that made them do it. They had to do it? The thing is, what about us - the users?