She’s so low-key, in fact, that an employee of Cleveland, Ga.–based Access to Capital for Entrepreneurs (ACE) thought the notification of a $10 million gift from Scott was a spam or phishing email, Grace Fricks, president and CEO of ACE, told Fortune.

This was the largest gift ACE, a nonprofit Community Development Financial Institution, had ever received. Launched in 2000, the nonprofit offers loans and advisory services to new businesses in Georgia, focusing on helping women, people of color, and people with low to moderate incomes. Scott had previously donated $5 million to the organization in 2020.

The latest gift came “completely out of the blue,” Fricks told the Atlanta Journal-Constitution. “I thought, you know, she’s probably calling because they’re going to be doing a blog or a story on the impact of MacKenzie Scott’s previous awards, and she either wants to talk to me or wants to talk to one of our clients who benefited.”

Scott, billionaire ex-wife of Amazon founder Jeff Bezos, has made it her mission since her 2019 divorce to offload much of the fortune she gained from the demise of their marriage. As of March, Scott had donated a whopping $17.3 billion to more than 2,300 nonprofit organizations but is still worth an estimated $34 billion, according to Forbes. She used to publicize the gifts made in online blog posts and an online database called Yield Giving. But now, gifts are only typically publicized by the recipient. 

Scott’s gift to ACE came just in time as the nonprofit is in year two of a five-year strategic growth plan to provide 1,500 underserved small business owners with $300 million in loans. The unrestricted gift will help ACE achieve those “ambitious goals,” Fricks said, along with 100,000 hours of business consulting services.

“It is one thing to dream about what  ACE could achieve if we had the resources,” Fricks said in a statement to Fortune. “It’s entirely a different mindset when you start with having the resources so you can envision and implement a better reality for your mission.”

Scott’s vast fortune and tendency to give fascinates philanthropists and regular people alike. 

“MacKenzie Scott has mobilized a staggering $17 billion to 2,300+ nonprofits globally since 2020, largely through unrestricted seven-figure donations rooted in the growing calls to center on the knowledge, relationships, and expertise of leaders on the frontlines of social change,” Sara Lomelin, CEO of Philanthropy Together, wrote in an op-ed published by Fortune in August. “Brava.” Scott typically donates to organizations focused on equity and justice, education, and health and economic security and opportunity—although a couple of her major gifts made in the past year focused on housing. 

But what’s mysterious about Scott is that she’s not nearly as flashy as other major philanthropists. She’s a billionaire dozens of times over, yet doesn’t put herself in the limelight. In fact, Scott is infamously difficult—if not impossible—to contact; indeed, attempts by Fortune to reach Scott to comment on this recent gift were unsuccessful. 

Although Scott’s gifts undoubtedly have an impact on beneficiaries, other experts argue her lack of transparency and contact with recipients doesn’t make much long-term impact. 

“There’s no long-term relationship,” Pamala Wiepking, a professor at the Lilly Family School of Philanthropy at Indiana University, who has studied the impact of unrestricted giving on nonprofits, told the AP. “What they are saying with trust-based philanthropy is to offer support beyond a check, and that’s typically not what she is doing.”

Still, the sheer volume of giving by Scott is impressive. In March, she announced she was giving $640 million to 361 small nonprofits that responded to an open call for applications. Of those, 279 nonprofits received $2 million, and the remaining 82 were given $1 million. That makes ACE’s donation seem even more sizable. 

“We give people a chance when others won’t,” Fricks said. “I believe Ms. Scott believes her gift will increase our impact and attract others to join with us.”