The NFL is working on its efforts to reinforce the league's gambling policy to players in the wake of a rash of recent violations.

All rookies will now have to attend mandatory education sessions, and a group of league officials is making in-person visits to team facilities to emphasize and clarify what activities are prohibited amid the rapid proliferation of sports gambling.

"The world has changed over the last few years," Jeff Miller, NFL executive vice president of communications, public affairs and policy, said. "... The availability of our phones and [with] a couple of touches, and all of a sudden, you can place a bet on many different things was not available a few years ago and is available now.

"So, sports gambling has a great deal more presence in people's lives than it did just a few short years ago, which means for us as [a] sports league -- where integrity of the game is the highest single principle -- that we have to be thoughtful and careful and scrutinize how we share information and educate people around the rules that govern it."