Why not just have an easy button that you can click saying Do Not Allow Reply All?
I know that there are some ways you can limit reply-all availability, like in the URL linked here. But there’s a note: If recipients open this email in other mail applications except Microsoft Outlook, such as opening on web page via web mailbox, they can reply all this email.
I’m semi-tech savvy but I’m no programmer. It feels like it should be easy to do, so either I’m totally wrong or email services are really missing out on a great thing they could do.
There’s a special hell for everyone sharing tips to stop people from reply all’ing
Why? BCC is the solution and has been part of email since at least 1990. I’m not condoning a dogpile on OP, but this is a solved problem.