Results: I did not do the noreply filter. I tried this instead. I have a xxx@me.com iCloud account, my wife has a xxx@aol.com apple id/icloud account. If I create the list on her ios device, share it on pc at icloud.com things work great. The list shares and her aol email does not get email notifications, nor does my me.com . I created a couple of other lists with my me.com id and same problem. I get emails every time a item is added or check off by her. So this "undocumented feature" and "locked feature" seems to be unique to me.com apple accounts.
As others have said icloud is a work in progress, so they may change the feature set in the future. It would be great if I got a banner notification she added or completed a task, but an email is just insane.
This solution will not work for everyone, but if one user has a non apple domain apple ID then it might work for you.
Good luck.