Will forwarded mail get rejected if I implement a reject policy?

It is true that forwarded mail has traditionally been an issue. However, there are two variables to consider:

1. ARC (Authenticated Received Chain) was recently created to address the authentication issues caused my indirect mail flows.
2. When leveraging observation mode, you will be able to actually see the impact of moving to a reject policy. Often times, the impact is overestimated and the actual impact is negligible/non-existent.