Slack intensifies a war of words

The competition heats up between Microsoft Corp. and its smaller rival Slack Technologies Inc., as the companies struggle in the market to provide software to help workers communicate and complete a variety of office tasks.

After Slack's First Revenue Report Since debuting in the public market, the company's CEO shared anecdotes about major customers who he said pay for Microsoft's comprehensive Office 365 software, but still use Slack as his primary collaboration tool instead of the tech giant's competing product …