[tl;dr: Originated anti-spam math used in SpamSieve, SpamAssassin and others; did database consulting; helped start Athenium, LLC; have expertise in recommender systems, Python, and relational databases. Enjoy music and chess.]
After getting my B.A. in Mathematics, way back in 1978, my original plan was to become a professor of mathematics. I enrolled in NYU's Courant Institute of Mathematical Sciences, supporting myself through database-related consulting. (I worked on database that were huge for the time, mostly at NY Telephone.) I quickly noticed that the computer industry was very rich in interesting opportunities beyond consulting. Before long I pulled out of graduate school to spend my evenings in entrepreneurial activities -- which I funded by continuing to consult during the day.
In the mid-1980's I founded Microvox Systems, Inc., to create a voice mail-based dating service in New York City, which was called 212-ROMANCE (the name was also the phone number). As far as I know, it was the earliest such service to go into development, and was one of the earliest voice mail services of any type. As a way of determine whose recorded "personals ad" should be played for who, I implemented an idea now referred to as collaborative filtering. As far as I have been able to determine from speaking to people in the industry, this was the very first time collaborative filtering was implemented in a commerical system, and may have been the first collaborative filtering implementation in any context. Collaborative filtering is now used for such applications as recommending movies, music, and even Web sites.
After moving to Maine, I continued working on the mathematics related to collaborative filtering. That led to a spin-off algorithm that turned out to be useful for spam filtering. My mathematical suggestions for spam filtering are included a number of spam filters, including Mozilla, AGMSBayesianSpam, Bogofilter, DSPAM, Eudora, Hexamail, Popf, SpamAssassin (PC Magazine Editor's Choice), Spambayes, and SpamSieve (MacWorld Software Product of the Year). For details, see My March 2003 Linux Journal article, A Statistical Approach To The Spam Problem. Over time I've noticed online references to my suggestions on websites in Czech, Dutch, Finnish, French, Japanese, German, Russian, and Spanish, which has been fun. At that time, I was a Research Director at ActiveState, advising them on spam technology.
As VP/Advanced Technology and 3rd employee of Athenium, L.L.C., I managed the development of TeamThink, a collaborative educational application. My tenure ran from the earliest stages until the product was at use at universities including Stanford, Yale, and Tufts, and at major corporations. At that point, I felt that the product had enough momentum that my departure to pursue other interests would not harm the company's prospects. I am one of the inventors named in Athenium's original patent for that product, and wrote the specification.
For most of the 2000's, I was CTO of Emergent Discovery, LLC. That company made some good technology but never found its business niche, and is now basically a shell. I left for reasons discussed in a blog post. Right now, I'm looking at various opportunities and deciding what to do next. Whatever it is, it'll be fun.
In my personal life, I'm happily married to Deborah, a retinal surgeon in Bangor, Maine, and have two fantastic kids, Isaac and Noah. My hobbies are songwriting and chess. (One of my songs is available on Smithsonian Folkways; they put it on Amazon.) But work and family has kept me from spending all that much time on my hobbies in recent years!
 I appreciate the "Thanks, Gary!" note on SpamAssassin's credits page.
 For your amusement, ancient ads for 212-ROMANCE are still viewable online.
my family, my business, great music of all kinds (classical, late bebop-period jazz, interesting songwriters like Leonard Cohen and Randy Newman), programming, statistics, songwriting (I play guitar and write), movies...