The issue is that once a email provider has you as a customer they know that you give out your email and potentially hundreds of people know it to contact you. If you change it, they know it's a huge hassle and they have you by the balls. They offered me a free account for many many years then suddenly they decide it's uneconomical for them. So they basically say pay up or lose your email. This is what the danger is. Even if it's a paid account they still can raise the price on you as they wish because you are locked in or at least they think so.
Better off staying on an email provider that is based on advertising for their revenue like Gmail, Yahoo, AOL, Hotmail ect. It (almost) assures you that it will stay free.
BTW, their GUI looks like it was designed by a pimple faced 14 year old sitting in his mothers basement.