Emailing receipts to members

Hi folks. I wanted to hear about current practices and plans around sending an electronic receipt, instead of printing one out. I hear that chains are doing this. It's true that our member data is (largely) stored in our Catapult POS system.

Are any of you regularly emailing receipts?

Does it get sent automatically for those with a "flag" set, or is action by the cashier required each time?

Anything else we should think about?