I have had my share of replay-all e-mail chains, and abeit it was a slow and painful process, I managed to un-train the people doing it eventually be showing how e-mail was not an effective means of communication for the issue (which would have the e-mail version of creep scope as new ideas/thoughts were added).
I did this by taking the e-mail and splitting it up (since they quickly became huge amounts of text) into issues, and then using an issue tracking software to manage them. I have used both github and slack for this, but I am sure there are plenty of other options as well. Basically this lets people focus in on the specific issues that they care about, while still having access to everything. Better yet, you can @mention someone if you feel they particularly should have a say in something, whereas if you simply included them in the reply-all, there would be a large amount of irrelevant text for them to sort through. This worked well for the majority of types of chain e-mails with reply-all that I was facing, although not all, mainly scheduling ones. For scheduling, again I propose using another software - while many e-mail clients have scheduling features, they sometimes aren't the greatest, so I have sometimes resorted to making excel documents with each person's name and available (and preferred) times (make sure it's editable by all).