Its kind of the point to frustrate the receiver. If I don't want you archiving or resending what I sent to you, I can use this feature to do that. Sure, you can jot down the information, make a screenshot or similar if you wish to override my wishes, in much the same way as you could record a phone call, but the onus is on you. Hopefully you stored my confidential data somewhere secure and GDPR compliant, and not left a copy in your mailbox as a lawsuit waiting to happen. And if I protect emails this way that I would be happy for you to archive, then I'm an idiot.