wpmu_signup_user_notification

@param string|false $domain     Site domain, or false to prevent the email from sending.
@param string       $path       Site path.
@param string       $title      Site title.
@param string       $user_login User login name.
@param string       $user_email User email address.
@param string       $key        Activation key created in wpmu_signup_blog().
@param array        $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
@param string $content    Content of the notification email.
@param string $domain     Site domain.
@param string $path       Site path.
@param string $title      Site title.
@param string $user_login User login name.
@param string $user_email User email address.
@param string $key        Activation key created in wpmu_signup_blog().
@param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
@param string $subject    Subject of the notification email.
@param string $domain     Site domain.
@param string $path       Site path.
@param string $title      Site title.
@param string $user_login User login name.
@param string $user_email User email address.
@param string $key        Activation key created in wpmu_signup_blog().
@param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
@param string $user_login The user's login name.
@param string $user_email The user's email address.
@param string $key        The activation key created in wpmu_signup_user()
@param array  $meta       Optional. Signup meta data. Default empty array.
@return bool