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

All rookies will now be required 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 six "key rules" of the gambling policy that the league officials will emphasize are:

1. Don't bet on the NFL;

2. Don't gamble at your team facility, while traveling for a road game, or staying at a team hotel;

3. Don't have someone bet for you;

4. Don't share team "inside information";

5. Don't enter a sportsbook during the NFL playing season;

6. Don't play daily fantasy football.

"The world has changed over the last few years," Jeff Miller, NFL executive vice president of communications, public affairs and policy said in a media availability Tuesday. " ... 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."

The mere decision to schedule the session with reporters is itself noteworthy and can be seen as a reaction to recent events. Five NFL players were suspended in decisions handed down in April.

And this month, an investigation focused on Indianapolis Colts cornerback Isaiah Rodgers came to light, with sources telling ESPN Rodgers is believed to have placed bets on Colts games. Miller, citing the ongoing investigation, declined to comment on the status of the Rodgers probe.

The league is also focused on intensifying its monitoring and policy enforcement efforts with the help of external monitoring firms and the various sportsbooks. The NFL is hopeful this will create additional deterrence.

"We have a number of resources and tools both internally and externally," said Sabrina Perel, NFL vice president and chief compliance officer. "We have to continue to be as robust as possible. So, it's multiple tools and resources that we're using. And I do think as time goes, those will continue to mature and develop and there will be things that we might be doing two years from now that we're not doing today."

The sportsbooks, Perel said, are working in conjunction with the league and will alert the NFL if and when a player places a bet under his own name. Geolocation technology is a big part of these efforts, too, as bets can be traced to a player's home, for instance.

The easy access to gambling has created some ambiguity in the gambling policy, but Miller rejected that as a possible excuse.

"It comes back to, in large part, a couple of rules that have existed as long as anybody can remember," he said. "Don't bet on the NFL. That's not new because sports gambling is more available. That's always been the case. And don't bet when you're at work, wherever work happens to be in that moment. That's existed for a long time."

The latter part of that statement was a reference to bans on players placing bets on non-NFL events while at the team facility or while traveling with the team.

"The rules around it are pretty straightforward," Miller added.

When it comes to any potential mixed messaging because of NFL owners' willingness to enter sponsorship relationships with sportsbooks -- even while NFL coaches and staff are prohibited from placing wagers of any kind and players are subject to tight restrictions on their gambling activities -- the NFL insists there is no double standard.

"It's just a little bit of apples and oranges," Perel said. "... At the end of the day, what that is about is bringing in new fans, keeping fans engaged, giving them the opportunities to engage in these things, versus what we all do personally and what we should not be doing to protect integrity."