About Mary Ann Horton - Mary Ann Horton

In October 1997, Mary Ann Horton persuaded Lucent Technologies to become the first Fortune 500 company in history to add transgender-inclusive language to its corporate nondiscrimination policy. The five words she proposed “gender identity, characteristics, or expression” became the template that Apple, Avaya, IBM, Xerox, Chase, and eventually 95% of Fortune 500 companies would follow. The research she conducted proved that gender affirming care coverage costs companies less than 40 cents per insured per year. That research shaped the Human Rights Campaign’s Corporate Equality Index criteria that corporations still use today. Out and Equal Workplace Associates presented her with the 2001 Trailblazer Outie Award for this work.

She is also one of the foundational architects of the modern internet. At UC Berkeley in 1981, she created uuencode, the first binary email attachment tool. She led Usenet from a 10-site network to over 5,000 sites worldwide. She was a driving force behind the adoption of the user@domain.com email format, helping standardize how the world communicates. Her 1981 PhD dissertation created Babel, the first real-time code error detection system and the direct forerunner of tools like Microsoft Visual Studio and Eclipse. She contributed to Berkeley UNIX and helped shape what became UNIX System V.

Mary Ann Horton, PhD, is a transgender activist, computer systems architect, internet pioneer, keynote speaker, and the award-winning author of Trailblazer: Lighting the Path for Transgender Equality in Corporate America. She is an assisting minister at First Lutheran Church of San Diego and the recipient of the 2025 Clarence E. Anderson Peace and Justice Award from SoCal Lutherans.

She has been featured in VICE, The Daily Beast, Google Arts and Culture, Salon, Diversity Factor, and SHRM.

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