I haven't gotten as many as 100, but I regularly get bombarded with 10+ notifications for the same message. I report all of these to the relevant folks at Microsoft, and been doing this for months no... zero effect. Do open a support case though, when they reach some critical mass of tickets on this they might actually do something about it.
Well, Teams is meant to replace email and let you be more productive and less distracted.. :D
On a serious note. I think they got rid of email notification from channel notifications settings (new one). Maybe it is not yet released wide or maybe you still get emails if your are not online in Teams?