I'm linux administrator, I know how to properly manage linux - that is why I bought N900. But not for making basic software like email - it should be build in without any errors / missing points.

I need complex device with Linux, but I do not want something for testing / learning, I want to use it.

That is simple. If nokia is selling internet tablets without working email (with proper manage IMAP connection) - do I need to make my own software? Ok, I will but I want such device for free.