When he first read the email, Will Novak, from Arizona, thought it was a scam.
"It seemed so urgent, like one of those emails you get from a 'prince' asking you to send them money," he told the BBC.
The email, titled Angelo's bachelor party, had been intended for a small group of friends. It set out the details of an upcoming ski trip to Vermont, to "send Angelo off" into married life.
Will doesn't know anyone called Angelo. He decided to reply.
It was that decision that started what Will calls the "strangest" week of his life.
"I do not know who Angelo is," Will wrote. "I am a Will Novak, who lives in Arizona. Vermont seems like a very far way for me to travel for the bachelor party of a guy I've never met. That being said, count me in."
Will describes his reply as a joke. He offered to bring along his "sweet Nintendo Switch" games console or a selection of Sudoku puzzles, if that was more to Angelo's taste.
"I didn't expect them to respond," Will said, "but two days later, they did."
The group of friends, including Bill Novak for whom the initial email was intended, urged him to come along.
"If you think we are kidding we are not. You better be coming, as we all are all dying to meet you," they wrote. "Not only will this be a weekend Angelo will not forget, it will be one you surely will not forget as well."
After posting the email exchange to social media, Will's story quickly went viral, making headlines around the world and spawning the hashtag #AngelosBachelorParty.
Will said the reaction to his post had been "unbelievable" but admitted that he had had a couple of reservations.
Other than the fact he hadn't skied in 20 years, Will was also concerned about funding the impromptu trip.
On the recommendation of a friend, Will decided to set up a GoFundMe page. In under two hours, he surpassed his $US750 ($NZ1105) goal, eventually raising more than $US4,000 ($NZ5900).
Will is going to give any leftover money to Angelo and his fiancee, who are expecting their first child, as a wedding present.
Will described the weekend as "fast paced", "high energy" and "truly surreal".
When he picked up his rental car, it had been upgraded to a Maserati, which was quickly filled with cases of beer donated to Angelo's stag do by a local brewery.
The group welcomed Will with fireworks and a heavy mental concert, with Angelo on guitar.
Despite sleeping through his first skiing lesson, Will said he "did all right" on the slopes.
"I skied into a man and we fell into a fence together. But it was super-slow speed and wasn't a big deal."
Asked what the best part of his "bizarre" week as a viral star had been, Will said "the general feeling of openness and friendliness" he had encountered.
"Reflecting on it, I could get pretty sentimental really. It's a great lesson in being open to the universe and to others.
"If a door opens, walk through it. You regret the chances you don't take, rarely the ones you do take.
"I've always been a class-clown type and knowing I made thousands of people laugh makes me so happy."