Sometimes, access to the top starts with something as simple as a stamp. General Motors CEO Mary Barra has noted that she responds to “every single letter” she receives.

Despite leading a nearly $75 billion automaker—and the fact that AI has turned once-tedious tasks such as drafting emails into seconds-long chores—Barra still writes back the old-fashioned way: with pen and paper.

The notes she receives range widely, from loyal Chevrolet drivers sharing their car’s nickname to schoolchildren worried about their family’s future after the closure of a General Motors plant. But positive or negative, the letters still get a response.

“I get [letters] from customers … when their odometer turns over to 200, 300, 400,” Barra said at the New York Times DealBook Summit in December. “I also get letters from consumers who are unhappy about something, and I respond to every single letter I receive. To me, this is such a special business.”

Even as one of the busiest executives in the auto industry—repeatedly topping Fortune’s list of the Most Powerful Women in Business—Barra has consistently treated intentional communication as part of the job. It’s a habit she’s carried throughout her rise at GM, from the assembly line to the C-suite. “You won’t always be right, but no one’s right all the time,” she said in 2023.