Old internet geezers like me remember when in order to send a binary attachment you had to uuencode into 7-bit text to get it across the internet. It wasn’t long before email clients, web based and otherwise, did this for you transparently. But it was my understanding that the conversion to 7-bit still had to be done at some layer.
Is this still the case? When I send an email from Gmail with binary attachment to say, Yahoo mail, is there still a 7-bit step involved requiring uuencoding? Or is it 8-bit end to end now? Email is notorious for being still of archaic design, so it would not surprise me if there still some 7-bit linkages still.