Slack announced today that it has acquired Astro, the Bay Area startup behind email assistant, Astrobot. The deal, which marks Slack’s largest to date, will go a ways toward helping the popular enterprise chat platform achieve its vision of fully integrating workplace mainstays like email and calendars into its channels.

As Slack notes, the company hopefully predicted last year that channels would usurp other forms of business comms in the next seven or so years. Achieving that optimistic goal, however, will mean convincing business users to shift from mainstays like email.

“We’ve taken some steps to make it possible to integrate email into Slack,” the company writes, “but now we’re in a position to make that interoperability much simpler and much, much more powerful. Our goal is to make it as easy as possible to help teams shift conversations to where they would be most productive — in a channel, alongside the relevant context and software tools teams use at work, from ServiceNow and Salesforce to Workday and Box.”

Astro was founded in 2015 by Zimbra cofounders, Andy Pflaum, Roland Schemers and Ross Dargahi. Last year, it introduced Astrobot (along with $8.3 million in funding), a Slack app that integrates email and calendars directly into the chat platform. Among other things, it lets users search both at once, without leaving Slack.

“And as we explored with Slack how to bring together messaging, email and calendar,” Astro wrote in a blog post announcing the move, “it became evident that we would have the biggest impact on workplace communications and realize our original vision by joining Slack.

The standalone Mac, iOS, Android, Amazon Alexa, and Slack apps will be shut down on October, with signups for new users being disabled immediately. Existing users will still have access to changes made through the app, courtesy of syncing. Most of the company’s roughly 30 or so employees will be making the transition to Slack.