Trending @Infosys; Delivery Managers are not following ethics.

Previously I am part of one internal project. I spent more time on implementation of custom applications like out of box applications, 25% of project work I did there, Now I came to another external project. Due to the internal politics the Delivery manager did not mention my name in the appreciation mail (it sent the entire Infosys) even though some people are not part of that project also there. I feel injustice about this Delivery managers.