If Slack can dovetail seamlessly with how people behave, feel like second nature to use and strongly appeal to employees, taking it away could become “like taking off your astronaut helmet in space,” Mr. Butterfield said. Microsoft said users would embrace Teams because it had strong encryption and global support and worked seamlessly with software they already used, like Excel. “I’ve been building software for 15 years, and I’ve become more attuned to how the average person will interact with and experience software in the last 18 months here than in the prior 13 years,” said April Underwood, who joined Slack as vice president of product in 2015. The company behind it, Slack Technologies, found success by combining something that Silicon Valley fetishizes — rich data on how people use a product — with something it often overlooks: How do people actually feel while using it? The executives who run those businesses within Microsoft must “compete for budget and mind share and attention,” he said, providing an opening for Slack to gain users while Microsoft managers wage internal wars. “Building a product that allows for significant improvements in how people communicate requires a degree of thoughtfulness and craftsmanship that is not common in the development of enterprise software,” Slack wrote in an open letter to Microsoft that ran as a full-page ad in November in .
