Eric Mabius Says Signed, Sealed, Delivered Franchise 'Keeps Getting Better' After 11 Years (Exclusive)

• A new installment of Hallmark’s Signed, Sealed, Delivered franchise, A Tale of Three Letters, premieres on Friday, July 12, after three years
• The cast filmed two SSD movies simultaneously in the spring, with the second planned for a 2025 release
• Star Eric Mabius tells PEOPLE the new movie promises a “new type of happy ending”

After three years, the POstables will return to the small screen when a new Signed, Sealed, Delivered movie premieres on Friday, July 12.

“We have such a fervent fan base,” star Eric Mabius tells PEOPLE. “Each time we come back together to do another movie, there seems to be so much more behind it, in a lot of good ways. There's a lot of heaviness, but also so much delight in being together. I think we're in such a unique place with the show and having 11 years to evolve as human beings, getting the characters doing the same.”

Mabius, 53, calls reuniting with his costars for Signed, Sealed, Delivered: A Tale of Three Letters “more of an emotional experience than any of us had anticipated in a wonderful way.”

“It doesn't ever feel like work when we're together,” he adds. “Having old dear friends to act with in front of the camera is, I don't know how else to describe it other than it's just fun. It's a joy.”

The next installment follows The POstables as they attempt to identify the recipients of a trio of dead letters — and the case ends up hitting particularly close to home for Oliver (Mabius), Shane (Kristin Booth), Rita (Yan-Kay Crystal Lowe), Norman (Geoff Gustafson) and Charley (Rhiannon Fish).

“If you look at Oliver in the pilot and where he is now, he's still the same person, but vastly, vastly different,” Mabius says. “That's what's so great. We find ourselves making reference on set to, what would Oliver do? Because in some ways these are the idealized version of ourselves. What I do love about these movies is that, in different ways we see Oliver starting over in many ways and a vulnerability in each movie in very different ways. The friendship that he's had with Norman for all these years continues to deepen in such interesting ways.”

A Tale of Three Letters also finds Oliver and Shane settling into married life.

“Shane and Oliver are such strong, distinct, very different personalities and fully evolved in many ways,” Mabius says. “And like in our own lives, learning how to make the space for someone else in your life is different than actually joining together. There's a lot of friction as we go through this journey and each of them realizes that it's not just about living under someone's roof, it's learning how to change. It's kind of a wonderful conflict — it's not fun all the time, but where we end up is so fortifying somehow.”

Oliver and Shane will tackle those conflicts in a way that Hallmark viewers might not expect.

“Hallmark is really backing up their intentions to evolve, to bring new product to the audience, but to challenge them in different ways,” Mabius teases. “There are certain boxes that have to be when people tune into Hallmark, and we get that, but never dumbing down the material for the audience, injecting it with real life and finding a way to bring about a new type of happy ending in these storylines.”

Mabius hints that Oliver’s mother abandoning him and his father Joseph “only being there for him financially” will get also “examined again in a new way.”

The father of two and his costars filmed two SSD movies simultaneously back in the spring, with the second one, To the Moon and Back, planned to premiere in 2025.

“It was challenging doing two,” Mabius admits. “Back to back is one thing, but simultaneous is a whole other thing. It reminded me of a little bit of shooting Ugly Betty back in the day, when we would do two episodes at the same time. But these two movies are so different in so many ways emotionally and where each of the couples are in their evolution.”

As for what awaits Oliver and Shane in the next movie, Mabius thinks they’d make “great parents.”

“Takes a village to raise a kid, and they have such a wonderful village around them,” he says. “Over these years, they've assembled such a length and breadth of a support system. I think tackling a conventional problem in an unconventional way is part of the reason why people keep watching the show.”

Mabius says he loves appearing in Hallmark movies and offering a touchstone to male viewers.

“In the social media interactions, at the Christmas convention and at other Hallmark conventions that I've attended, the husband will step up and say, ‘I just want to thank you,’” he continues. “Norman and Oliver or Joseph and Oliver having not perfectly neat male to male friendships or father and son conflict. We don't shy away from conflict, but we don't present a problem without trying to present at least one possible solution to that. And having male audience members get that, it's really refreshing.”

Mail carriers also appreciate the Signed, Sealed, Delivered franchise. “In my hometown in Amherst, there was a postal worker that delivered our mail when I was going to high school, and I had bumped into many years later and was just beaming with pride,” Mabius recalls.

He assures that, even 11 years in, SSD will continue to show viewers something new.

“I'm just so proud that we continue to build out an audience,” Mabius says. “It's like peeling back layers of an onion or a flower that continues to keep opening. It just keeps getting better."

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Signed, Sealed, Delivered: A Tale of Three Letters premieres Friday, July 12, at 9 p.m. ET on Hallmark Mystery.