Slack Welcomes Microsoft to Messaging With Full-Page Letter That Echoes Apple’s Famous ‘Seriously’ Ad

 By Kristina Monllos November 2, 2016, 11:15 AM EDT Advertising & Branding Slack co-founder and CEO Stewart Butterfield boasted about the ad on Twitter. Twitter: @stewart Slack founders are taking marketing lessons from Steve Jobs. The workplace communication company took out a full-page ad in today’s New York Times, ahead of Microsoft’s Office event which […]