Horton contributed to Berkeley UNIX (BSD), including the vi editor and terminfo database,[1][2] created the first email binary attachment tool uuencode, and led the growth of Usenet in the 1980s.

Finding an interest in computer programming in 1970, Horton moved to San Diego County in 1971, and quickly fell in love with California.

[5] In 1981, high school student Matt Glickman asked Horton for a spring break project, and the two designed and implemented B News,[6] which offered major performance and user interface improvements needed to keep up with the explosive growth of Usenet traffic volume.

Each site ran Steve Bellovin and Peter Honeyman's pathalias program[13] to create a locally optimized email routing database from this map.

Harrenstein convinced the others to support the creation of six top level functionally domains COM, EDU, ORG, NET, GOV, and MIL.

In 1992, Horton created an internal email package for Bell Labs called EMS (Electronic Messaging System).

This system supported many email addressing formats, including those that dynamically queried the POST directory: In 2000, Horton joined Avaya, where she was the Sr.

Finally fulfilling a lifelong dream, Horton moved from Columbus to San Diego in 2007, joining Sempra Energy's Transmission Grid Operations team.

Adopting the name Mary Ann in 1987, Horton founded Columbus' first transgender support group, the Crystal Club,[20] in 1989.

Horton asked for its inclusion in Lucent's policy, and recommended the language "gender identity, characteristics, or expression".

[22] Despite controversy about the ability of corporate America to deal with a part-time crossdresser, Horton's workplace experience was positive.

She appeared as Aurora, a business executive, in a public service announcement advertisement for Stonewall Columbus entitled The Boardroom in June 2003.

Over the next few years, she took appropriate medical steps, and legally changed her name to Mary Ann Horton and her sex to female.

[26] In the 1990s, most employer health insurance policies denied coverage for sex reassignment surgery (SRS) or anything related to it.

[27] and championed the inclusion of points for THBs in the Human Rights Campaign's Corporate Equality Index, which were added in 2005.

[28] In 2002, Horton gathered data from 13 of 15 major SRS surgeons to determine incidence, intrinsic prevalence, and average cost of SRS-related surgeries.

This data, presented at the Out & Equal Annual Workplace Summit[29][30] showed that the cost of THB coverage, previously believed to be very high, is actually very low, less than 40 cents per US resident per year.

She owns Red Ace Technology Solutions, providing discounted web hosting services to nonprofit organizations and small businesses.