Hello everyone,
I have installed OS X High Sierra on m iMac Retina 5K and apart some kernel panics I also get a very unusual feature: Mail simply does not work: it attempts to rebuild and import messages, yet crashes every time with the message " mail cannot import mail" or " make sure you have enough availabal space in your Home folder " ( which should not be the case, I have 89 GB free space on my SSD.
Many thanks for all your help,