Persistent Alerts

Persistent Alerts 2.4.0

No permission to buy ($15.00)
XF1 Version

Can I force everyone to be opted in by default and then allow them to opt out?
Yes. This was not done by default because it changes the behavior of the forum drastically and everyone may not like that. If you want it though you just need to execute this query:
update xf_user_option set sv_persistent_alert = 1