If you can access your email when using 4g and by webmail on a browser there would appear to be nothing wrong with your email account and the problem, as has already been suggested, would appear to be with your Dutch Internet Provider's systems.
Hi, @henfelin I mentioned your posts to our email team and they'd like to look into this for you. I've sent you a private message so you can send over your BT account details to the moderation team and we'll be happy to help.
