The parental units currently use a web browser to access their ISP hosted email.

They would like to move to a non-ISP dependent email.

I've set them up with a free outlook.com address.

What would be the best way to transfer their emails over?

I imagine the worst way is one by one forwarding all their emails to the new address?

I could download all their emails using the outlook program, but I dont think that would be able to upload?