Lawyers using free mail services like Hotmail, Gmail & iCloud?
Oh yes!
Security, privacy & lawyers legal obligation to confidentiality?
Good question!
I've written about lawyers in Norway using such services, and my own personal recommendations about it.
https://www.linkedin.com/pulse/lawyers-using-free-email-services-per-thorsheim-4fkee/

Lawyers Using Free Email Services
I have previously written a couple of articles about email security at law firms in Norway & Denmark. I have also written about email security at Apple iCloud, labor unions in Norway, the Norwegian National Security Authority (NSM), the Norwegian Data Protection Authority (Datatilsynet), and the dec