A man inadvertently found out how insidious workplace sexism is for his female colleague, and his story is gaining lots of attention on Twitter.

Martin R. Schneider (@SchneidRemarks), a writer and editor who lives in Philadelphia, PA, wrote that a client was being “rude” and “dismissive” to him over email. When he noticed his email signature was accidentally set to coworker Nicole Hallberg’s (@NickyKnacks) name, the two decided to do an experiment. They switched signatures for two weeks and came to a shocking-for-him, not-so-shocking for her revelation.

Hallberg’s workweeks were far easier than normal, while Schneider’s were abysmal.

You can read the entire story below:

After the story spread on Twitter, Hallberg wrote her own account of what happened in a Medium post entitled “Working While Female.”

She explained the sexism she faced in her office was worse than what she experienced over client emails. She recalled one time after she “survived the rigorous training process” that a male employee had not, her boss gave her a “compliment.”

“My boss complimented me and himself, saying that ‘I wasn’t going to consider hiring any females, but I’m glad I did. You should be proud, I had thousands of applications but yours stuck out to me, and made me decide to give hiring a girl a try,’” Hallberg writes. “Interesting. ‘Why weren’t you considering hiring any women?’ ‘Oh, you know. We’ve always had fun here, and I didn’t want the atmosphere to change.’”

That same boss, post-email experiment with Schneider, also didn’t believe their story. Hallberg wrote:

“He actually said ‘There are a thousand reasons why the clients could have reacted differently that way. It could be the work, the performance… you have no way of knowing.’ For the first time in two years, I *almost* lost my cool.”

Hallberg eventually quit the job and left her sexist boss behind. She told The Huffington Post that she wrote the Medium post because she “wanted people to get the full story” and felt the topic was “too important to stay shut up about.”

“We take this shit over and over and over again out of fear of the men in power, and it helps perpetuate it. I’ll always be understanding of a woman who doesn’t want to or can’t afford to stick her neck out,” Hallberg said, noting that she doesn’t think telling her story will hurt her chances of getting work in the future.

Hallberg also said that, since the lesson of their tale was to listen to women, she wanted her side of the story to be just as visible as Schneider’s.

“I thought it was important to have the whole thing also framed from my perspective, so that I was in control of my own voice, and had partial ownership of the story about me,” she said.

CORRECTION: An earlier version of this story stated the experiment only lasted a week.