I've tried it with various web browsers (Mac Safari, Mac Firefox, Windows Explorer etc) various users (admin and standard users) and various firmware versions (68.51.1 and 68.59.1 on a c405).
Called the UK helpdesk yesterday, but they didn't pick up on part of the problem I was having (that I couldn't enter the e-mail adress) and told me I coulnd't set a default user e-mail address for use on a c405!
I am dealing with a bug preventing me from editing a new user. Logged as Administrator, I create a new user "bob" and try to give him an e-mail address. The process never goes to the end as you can see in the video below. The wheel is spinning forever.