Hi Deralex,
In your case, I think an activation account system by mail would be a solution near from what you want.
If I had to resume how to do this there is two big steps :
- Enabled user bridges
- Included a link in your mail wich allow the activation
For more details click on the tutorial I've linked.
If you still have a problem after this or if you have questions don't hesitate to come back to us.
Good continuation and happy new year,
Ness