You can enable all new posters of a topic to be automatically subscribed using the options from the subscription plugin, but this is generally frowned upon – and note that it will only work on members who post after the option is enabled.

In fact giving users no choice in getting email notifications from a forum is generally quite bad practice, and not something that you can ‘force’ with SP..

As for yourself – being Admin, if you go to your admin panel, then forum > admins – you can enable email notifications on new posts and topics.

Hope this helps!