Hello, if i open a new topic and I would like mention user can they receive an email notification?
You can set it here: https://open.vanillaforums.com/profile/preferences
From admin panel there is an option to setup for all user o group user?
You can add $Configuration['Preferences']['Email']['Mention'] = '1'; to your conf/config.php and that will cause every new user to start with this setting.
$Configuration['Preferences']['Email']['Mention'] = '1';
But there is no easy way to change this for all current users. And that's good! Just imagine you have users who have decided not to get any mail from your forum and you simply change that and send them mails although they have actively decided against that. Such users would consider you as an evil spammer.
i make a migration, and old user?