My God, sorry.
I was way too sleepy and light headed yesterday, I didn't notice I wrote this message in the wrong subforum. My bad.
Anyway, I just found out that this issue happens only when I activate the "joomlapraise" template.
When I use, lets say, the "modern" template the e-mail field for registered users is automatically filled AND disabled. So even if I click on it I can't over-write the "Automatic" value.
BUT, when I use the "Magazine" template, the field is not disabled. Thus, Joomla believes "Automatic" is not a valid e-mail address.
Here's the link to my current joomla install:
www.gen-kai.com/portal
I have enabled the Joomlapraise template for you.
Username: testman
Password: test
Frontend language is now English.
Thankyou!