@skynet,

If you want continue to use wpForo please contact us via support[at]gvectors.com email address and send admin login details.

So why another forum plugin (Asgaros Forum) works very well ?

wpForo has own email configuration, this is the reason. It seems you've done some wrong configuration, or the FROM email/name is not trusted by email servers. There are dozens of answers on this "why" question. But we're going to help you to solve the issue, instead of debating around.