On the afternoon of Feb. 25, a Wednesday, Gabby Schilling received a long-awaited piece of mail: her acceptance letter to Salve Regina University in Rhode Island. She was also informed that she’d be pitching for the school’s softball team.

Her dad, retired baseball great Curt Schilling, was elated. He wasn’t at the family home in Medfield, Mass., when Gabby got the news, but at 2:53 p.m., he took to Twitter and posted this:

Schilling has 121,000 followers on Twitter. Within hours, he says, he started seeing some crass ­responses.

“They were vulgar things,” Schilling tells The Post. “Stuff like, ‘I’ll take care of your daughter, wink-wink.’ ” As a lifelong professional athlete, he says, that kind of talk wasn’t surprising, and he responded in kind. At 7:55 p.m. that evening, he tweeted:

Then came the deluge. One user who called himself “Hollywood” and went by the handle @primetime227 tweeted Schilling: “Teach me your knuckleball technique so I can shove my fist in your daughter.”

A user named TheSportsGuru (@Nagels_Bagels) joined in:

“Curt bleeds more from his sock than Gabby does from her ­p—- when she’s on her period.”

Hollywood: “Curt rocked the mullet — business in front, party in back…Gabby prefers the party in back. #ButtStuff2015

Then they wondered why Schilling hadn’t responded to them. As it happened, Schilling was responding to other users who were threatening to rape Gabby. He couldn’t believe it.

“I played 10 years in Philadelphia and five years in Boston,” he says. “I’ve heard it all. I have a very, very thick skin. I’m a guy’s guy — I’ve been in locker rooms, a theater

of war, and never in my life have I ever thought those things about a woman, much less said them.”

He kept tweeting. A day later, Gabby, who follows her father on Twitter, realized what was going on and sent her father a text.

“She was like, ‘Oh my God — what have you done?’ ”

Schilling didn’t respond. When he got home a couple of hours later, he found Gabby crying.

“She was devastated,” he says. “She went to my wife distraught, sobbing. She was upset with me because she thought I was responding to the worst ones. She said, ‘I’m ruined. I can’t go to ­college.’ ”

Schilling’s wife, Shonda, is also on Twitter. “She was mortified,” he says. “She wants to murder someone.” He begged his wife not to respond online.

The three of them sat and talked. Gabby is 17 years old, and like so many kids who’ve grown up in the digital age, she wanted to just ignore it until it went away — “shake it off,” as it were.

Her father felt differently — that there should be pushback, that these people, whoever they were, should be held accountable.

“I said, ‘Gabby, listen — I apologize if you’re embarrassed, but there are certain things that aren’t allowable.’”

Schilling thought about what to do. “Five years ago, I would’ve gotten in the car and beaten them up,” he says. “But I also have three sons, and I have to teach them that there’s a right way and a wrong way. So after I decided I wasn’t going to try to hurt them, I decided to find out who they were.”

It was easier than anyone might think: Schilling, 48, began Goog­ling their Twitter handles, their online friends, tracking down their Facebook and Instagram pages, following all the little ­cyber bread crumbs we unknowingly leave behind each day.

“Within an hour and a half, I found nine of them,” Schilling says. He discovered not just their names but their addresses, their high schools and colleges, what teams they played on, their parents’ e-mail addresses.

Schilling reached out to all of Gabby’s bullies directly. He did not name those who apologized.

He thought it through some more and then decided to write a post for his blog, 38 Pitches.

It was nearly 2,000 words long and, he says, “my 57th revision.” Schilling wrote about his pride in his daughter, his facility with ­social media, his experience with and expectation of locker-room talk and his disgust with the online trolls who threatened Gabby.

“Tweets with the word[s] rape, bloody underwear and pretty much every other vulgar and defiling word you could likely fathom began to follow.”

He decided to publicly identify two of the worst offenders.

TheSportsGuru, Schilling wrote, was Adam Nagel, a student at Brookdale Community College in central New Jersey.

“How do you think that place feels about this stud representing their school?” Schilling wrote. “You don’t think this isn’t going to be a nice compilation that will show up every single time this ­idiot is Googled the rest of his life? What happens when a potential woman he’s after Googles and reads this?”

Schilling then identified “Hollywood” as a vice president of the Theta Xi fraternity at Montclair State University in northern New Jersey. Quickly, Schilling’s fans named “Hollywood” as Sean MacDonald, who worked part-time selling tickets for the Yankees.

Schilling, of course, led the Red Sox past the Yankees and on to the World Series title in 2004 — a historic postseason run that included playing one game on a stitched-up ankle that famously left his sock red with blood.

MacDonald was fired, and Nagel was suspended from school. Both of their Twitter accounts have since been deleted.

What Schilling accomplished within days garnered national headlines and has revived the question: How much should what people say or do online impact their lives — their ability to get or keep a job, stay in school, have their reputations, in minutes, publicly shredded? Should dumb tweets be taken that seriously?

“But I want young girls and women to know: You don’t have to take this.” - Curt Schilling

Schilling argues that there’s no longer any distinction between life online and offline: “People are saying, ‘Hey, Curt Schilling called out people on Twitter, and they got in trouble in real life.’ Twitter now IS real life — Facebook, Instagram, all of it.”

Parry Aftab, one of the nation’s leading experts in cyber security and part of Facebook’s five-member safety advisory board, agrees.

“I don’t think we even use the words ‘real life’ anymore,” Aftab says. “It’s life. When I saw what Curt did, I applauded his actions — he didn’t cower in a corner. This matters. It really matters.”

Research on cyber bullying is surprisingly thin, especially as children and teenagers are the most vulnerable.

According to a 2004 survey conducted by i-SAFE, 42 percent of teens had been bullied online and 58 percent didn’t tell their parents or another adult. A 2010 study conducted by the Cyberbullying Research Center found that 50 percent of teens had been cyber bullied, with between 10 percent and 20 percent reporting it as a regular occurrence.

While Aftab says the stats on suicide are low — only 150 people around the world have killed themselves as a result of cyber bullying — girls are particularly vulnerable to any sexually charged threats: sextortion, revenge porn, imposters.

If a victim is likely to harm themselves, Aftab says, “the first attempt will happen within the first 30 minutes of the threat.”

“Kids haven’t developed the coping mechanisms that adults have,” says Dr. Sameer Hinduja, a professor of criminal justice at Florida Atlantic University and co-director of the Cyberbullying Research Center.

“You don’t think this isn’t going to be a nice compilation that will show up every single time this ­idiot is Googled the rest of his life? What happens when a potential woman he’s after Googles and reads this?” - Schilling — On naming his daughter's bullies

“They don’t know how to compartmentalize. So kids internalize it; it feels like the walls are closing in, that there’s no escape. And victims often don’t want the bully to be confronted. They just want them to go away. Curt really crystallized that in his post.”

And as Schilling’s example shows, cyber bullying — especially of a sexual nature — is ­often so mortifying that a parent is the last person a kid would tell. But experts say they should.

Aftab points to the case of a girl named Nafeesa Onque from Newark. Several years ago, when Nafeesa was 13, another girl went online and created a fake Facebook account in Nafeesa’s name.

“She set her up for sexual attacks, posted nude photos of herself from the neck down and started communicating with members of local gangs as Nafeesa,” Aftab says. Why’d she do it? They liked the same boy. “That shows how, in so many cases, what happens online can go offline very quickly,” Aftab says.

In that case, it took law enforcement nearly two years to track down Nafeesa’s tormentor; meanwhile, Nafeesa refused to be bullied. She maintained her own original Facebook page, and her mother kept reporting the abuse to site administrators and the police.

Aftab and Hinduja say that in the majority of cases, victims of cyber bullying don’t know what to do — or that there’s anything they can do. Aftab’s 20-year-old organization, WiredSafety, offers free help to anyone in need but says that after all this time, not enough people are aware. “I’m on TV all the time, but clearly I’m not getting the word out,” she says. “Curt could’ve come to us, but he didn’t know we existed.”

Ultimately, Curt Schilling didn’t need outside help — and that’s what he wants everyone to take away from this experience. “You don’t have to be famous, and you don’t have to have money,” he says. “You just have to be really, really loud.”

It could be argued that Gabby’s online humiliation would never have become a national story had her father done what she wanted — ignored it. For her generation, the ingrained response to online targeting is “haters gonna hate” and “don’t feed the trolls.”

Yet Schilling didn’t just engage in flame wars: He publicly identified the pseudonymous online posters and asked how their schools could possibly abide such behavior. Whether public shaming is a healthier response, or a more just one, is something we as a society are still unsure of — as are the experts.

“I go back and forth,” Hinduja says. “I don’t want people to feel like they can always take justice into their own hands. But if law enforcement isn’t going to do anything about it, maybe this is something that will deter people.”

For Curt Schilling, a man who’s been famous for the bulk of his life, publicly shaming those two individuals may have felt like a proportional response. But none of us is immune from that lone tweet destroying reputations.

“Are we now going to have a society that pauses for a moment before posting something hateful?” Hinduja asks. “I don’t think it works that way.”

Without directly engaging, there are simple steps anyone can take to stop a cyber bully. Aftab’s and Hinduja’s organizations both work with service providers to get content removed swiftly, and Aftab works with law enforcement all over North America. Individuals can contact sites on their own and get action.

“You can block, you can report, you can set up protective mechanisms,” Hinduja says. “And targets need to know — when you click on ‘report,’ or report abuse, the person you’re reporting never finds out it’s you.”

Schilling, however, is gratified that his daughter’s bullies felt his wrath personally, that as a 48-year-old suburban dad of four, he could level some consequence.

He says that most of the aggressive tweets aimed at Gabby came from young athletes and feels that “all of those had to do with how people felt about me.”

Schilling got in touch with their coaches and parents, and many were made to write letters of apology.: “One of the anonymous tweeters is being recruited to play football.”

But one more digital misstep, Schilling says, and “he’s going to ruin that.”

At Gabby’s request, Schilling has stopped naming names.

“She’s already started to move on, and I need that to happen,” he says. “But I want young girls and women to know: You don’t have to take this.”