The massive heavyweight unification, which will double up as the first undisputed clash since Lennox Lewis v Evander Holyfield two decades ago, has now moved a step closer to reality.
Hearn says the deal has opened up more possibilities for dialogue between both sides and sees the encounter later this year.
“I believe it will. I do believe it will. The negotiations are opening up now. We’ve made an offer, they’ve made an offer,” Hearn told Sky Sports News.
“There are other models and offers to explore, more details to explore. But the conversation is ongoing.
“The positive thing to come out of this – whether it’s a PR move or has substance – it’s bringing the fight closer.
“From our side, absolutely no doubt that this is the fight Joshua wants next. I believe Wilder wants it next.
“I’ve written back and said we’d be very interested in that offer, but we can’t rely on your email. We need to see proof of funds and formal paperwork. There are lots to discuss.
“For a fighter to send another fighter an email, telling them about this money, is very strange.
“You can’t expect someone to accept a deal from a personal email from a fighter to another fighter. We have to see a contract and see the terms,” he added.
The fight is expected to occur in Las Vegas during the last two months of 2018, leaving the possibility of an interim fight for Joshua and Wilder open.
While Wilder’s latest outing stipulated by the WBC is against Dominic Breazeale, Joshua has been mandated to face Alexander Povetkin.
Both bouts could potentially take place in the late summer before the massive build-up begins to the Pay-Per-View blockbuster.
Whether Joshua and Wilder would want to risk another contest is an entirely different discussion, though.