We actually have users contact our help desk asking for the receipt not realizing it's already in their inbox or spam folder. I've considered adding an opt-out

We actually have users contact our help desk asking for the receipt not realizing it's already in their inbox or spam folder. I've considered adding an opt-out checkbox during checkout but I honestly doubt it would ever be unchecked and if it was opt-in we'd have users contacting support asking for it because they didn't realize they had to check the box. Either way it's one more toggle on the UI which I'm not a fan of unless absolutely necessary. I'm curious if you've run a business and experimented with not sending receipts, and if so how it played out?