I have been receiving these emails for flights since late March. I am not sure how much they rely on these emails for expected loads because if you don't click that doesn't mean you won't fly. Probably just to let you know you can receive a voucher if you don't want to take a trip anymore.
Also these emails come at the most random times ever, I have had ones sent from 5 months to 4 days before departure. I have never clicked on them knowing there is really no benefit in doing so.