For those who say employers are going to e-folios for expense reports, that may be true in larger corps but it certainly isn't true with a lot of mid & smaller size ones, nor is it true for those who are self-employed & who have to submit receipts to clients.
I work for a small firm and we have some self-employed contractors. We find emailed receipts and bills better all round. A paper receipt is just a computer one that's been printed out - I don't see any special mystique about it.