Thanks Klas for your answer.
Since last post, I've updated my site with joolma 3.8.13
after testing in my local site, site forms are OK, articles are well created in administration and database. When email adress for sending visitor confirmation email is with the domain name of my site, the email is sent.
When email adress for sending visitor confirmation email is with another domain name that the domain name of my site, the email is not sent.
Is this bug due to the local site, and will be solved in my online site?