NEW YORK — Ten years ago, CC Sabathia, Johnny Damon and Nick Swisher walked into the mailroom at Ahmuty, Demers and McManus. They were there to surprise Ranjit Seal and Melvin Williams, two employees with developmental disabilities who worked at the Manhattan law firm. It was the Yankees’ very first HOPE Week, which over the last decade has become a new tradition for a franchise that has so many.

On Monday, the Yankees kicked off the 10th anniversary of HOPE Week — when the Yankees take five days to recognize people, families and organizations with inspirational stories — with a special 10-year reunion at Yankee Stadium.

“These people do amazing things every day,” Sabathia said. “For us to be able to bring light to it is awesome.”

All past HOPE Week honorees were invited to attend. They were joined by Yankees players, coaches and front-office staff — Sabathia and Brett Gardner, who have both been Yankees for the full 10 years of HOPE Week, new stars like Gary Sanchez, coaches like Josh Bard and Marcus Thames, general manager Brian Cashman, general partner Jennifer Steinbrenner Swindal and more. There were over 200 people at the reunion.

“The HOPE Week family continues to grow, but the amazing impact of shining a light on what these amazing stories are — people that are making a difference in other people’s lives — is pretty special,” Cashman said.

During HOPE Week (HOPE stands for Helping Others Persevere & Excel), the Yankees surprise honorees in their own communities, at a place that symbolizes their accomplishments. Then each celebration finishes with a trip to Yankee Stadium for a game.

Monday’s reunion was a full day’s schedule — activities on the field at Yankee Stadium, meet-and-greets with the Yankees, a group photo, stadium tours, watching batting practice, a pregame ceremony and the Yankees-Rays homestand opener.

Honorees from the full decade of HOPE Week attended, including Seal and Williams from the inaugural HOPE Week.

“Wow. It’s surreal. The ultimate surreal,” Seal said. “Ten seasons. My goodness. I didn’t think I’d be standing here chatting with you guys. So much has changed — but the one thing that hasn’t changed is that so many people are telling stories of perseverance and how they’ve been able to succeed with things they do. It’s beyond amazing.”

So did others like Mohamed Kamara, a Sierra Leone civil war survivor who immigrated to the Bronx. Kamara was honored in 2010 as a high school graduate when Cashman, Sabathia and Reggie Jackson took him on a tour of the New York Stock Exchange, and Derek Jeter, Curtis Granderson and Thames took him to meet Mayor Michael Bloomberg at City Hall. He caught up with Sabathia on Monday, informing Sabathia that he just completed his master’s degree.

Before Monday’s game, members of 2011 HOPE Week honoree Daniel’s Music Foundation were scheduled to perform the national anthem. The ceremonial first pitch was to be thrown out by 2015 honoree Chris Singleton. Singleton was a baseball player at Charleston Southern University when his mother, Sharonda, was killed in the hate crime shooting at the Emanuel A.M.E. Church. Monday’s HOPE Week anniversary is also the four-year anniversary of the Charleston church shooting.

Singleton is now the director of community outreach for the Charleston RiverDogs — the Yankees’ Class A affiliate. His family attended Monday’s reunion along with him.

“Just seeing my son out here having a great time, and my little brother and my sister and my wife, everybody’s here fellowshipping today and having a great time, when this day usually brings sadness,” Singleton said. “It’s truly an honor to be here, man.

“Honestly, it’s just so great, because you never know if people understand your story and what you’re going through. But when you get honored with stuff like this, you realize people care. They’ve got your back.”

With this year being HOPE Week’s 10th anniversary, the week has several special features. Two HOPE Week flags are flying over Yankee Stadium this week, there are two HOPE Week logos painted on the field outside the first- and third-base lines, and HOPE Week jeweled bases are being used during each of the Yankees’ five HOPE Week games.

The first 25,000 fans at Monday’s game will also receive a commemorative HOPE Week 10th anniversary tote bag. HOPE Week T-shirts are also available at the Yankees team store.

By the end of this HOPE Week, there will have been 53 unique honorees over the 10 years of the initiative, plus five- and 10-year reunions. The honorees have come from seven different countries — the U.S., Dominican Republic, Ecuador, Haiti, Panama, Russia and Sierra Leone.

The original HOPE Week was the brainchild of Jason Zillo, the team’s vice president of communications and media relations. Cashman and the Steinbrenner family embraced it, and it’s now one of the Yankees’ most important annual events.

“There’s no shortage of tradition here. The fact that this has become that is humbling,” Zillo said. “There have been friendships formed and solidified over many years now. HOPE Week was never designed to be a fly-by. The idea is to really become intimately involved with a person or family’s story.

“You talk about the success of HOPE Week — to me it’s measured in smiles, not in anything else. The fact that so many people have walked away from the events we’ve had for them beaming and floating on clouds, it’s an awesome feeling being part of something like that.”

“They came to us, and we said, ‘This is incredible,’” Steinbrenner Swindal said. “This was a different whole idea. Taking one person who makes the world a better place — through hardship or whatever else, they decide to give their time or their energy or their ideas. Everybody here [today] is a family.”

Yankees players, including the team’s biggest stars over the years, have always embraced HOPE Week, too.

“Any time we get a chance to do something different than what we do every day — do something different and hang out with your teammates off the field and impact some lives — I think everybody runs to sign up,” Sabathia said.

“When you get the Jeters, the CCs, the Teixeiras, the Canos, and today’s stars, the Stantons and Judges, that’s where the impact comes,” Cashman said. “That was the [question] — how involved will they choose to be, want to be? And they’ve been all-in. … It’s just been amazing. Our players get as much out of it as they give — as does this franchise.”