Jack sent Dobson O'Gill, a fellow employee, an email expressing incredulity about recent new rules that were put in place by their CEO, Anthony House, or "Mr. H" in an attempt to commiserate with Dobson. He mentions that if the benefits were not so good, he would look elsewhere for employment.
Instead of agreeing or empathizing with Jack, Dobson lashed out, admonished him for writing him "seditious" content in light of the company's current email monitoring. Jack's ultimate fate is unknown.
Jack Maynard is mentioned only in Fallout: New Vegas.