Theoretically, from a functional requirements point of view, we could have that conversation over email. But that has many disadvantages. When we add people in over time, they wouldn’t have the history and all that. The real problem is that it’s just mixed up with a billion other things, like receipts for online purchases and wedding invitations and spam and unwanted solicitations from salespeople and important contracts. So having a channel is really valuable. It’s more like a private network that’s still accessible and has some visibility for administrators.

AP: One thing email is good at, though, is letting you talk to anyone. Does Slack have any ambition to one day let people communicate with each other in that way, like sending a DM to someone you don’t already know?

SB: Never say never, but probably not. We don’t need to kill email. We never set out to. Email serves so many purposes, and I think it has some real advantages, especially in being the lowest common denominator. That might sound like a negative, but I don’t mean it that way. It’s a universal standard. Anyone can run their own SMTP server or IMAP server. It’s a universal namespace, so anyone can message anyone else. But those advantages have a flip side. I still spend a lot of time on email, and I don’t expect everything to migrate, because there are new points of contact that arise over time. Introducing people is almost a canonical case of email usage for me these days.

When we imagine any two Slack users being able to DM each other, it’s only after some communication happened outside of Slack that can be a secure handshake. If you can message anyone, guess what will happen? The same thing that happens in email, which is that 99.9 percent of emails sent these days are spam. But for the incredible investment that Google and Microsoft and others have made over the last several decades in fighting spam, we wouldn’t be able to use email at all. We definitely don’t want to bring that into Slack. We’re carving out the pieces of email where we think we can make an improvement for a specific set of use cases. There’s no advantage to supplanting email completely from a business perspective. And also, there are a bunch of disadvantages, which is that we’d inherit all of this terrible crap that you have to deal with as an email provider.

AP: So the vision is not that, one day, all workplace communication will happen on Slack.

SB: No, only those parts which are best in Slack. The reality is that over time, organizations invest more in software. More software products are in use. Employees spend more time in software. The average number of cloud services in use for a large enterprise in the US is now over 1,000. We, as a 2,200-person company, buy software from over 450 different vendors—not different products, but different vendors. It’s kind of mind-blowing. So, the reality is, there are multiple modes of communication. Ideally, Slack can integrate with email, as it integrates with Salesforce, or Github, or AWS. If you have this lightweight fabric for systems integration, it makes all of the software more valuable. We used to say in our investor road show, leading up to listing day, that we want to be the 1 or 2 percent of your software budget that’s a multiplier on the value of the other 98 or 99 percent.

AP: Should we expect more Slack-and-email integrations then?

SB: There are some already. They’re still a little bit kludgy, but there are plug-ins for both Outlook and Gmail. Those are used in a bunch of different ways. At a small organization, maybe on their website they have public emails like jobs@companyname.com or sales@companyname.com. Rather than have those emails go to a mail distribution list, they can go right into a Slack channel, and people can reply from there. That’s been around for a couple of years. We also had a really early version of what is now a plug-in on the Outlook and Gmail side where you get a secret forwarding address. Any email you see, you could forward to Slack, and it shows up as an object inside of Slack—like a file—that can then be shared and commented on and stuff like that. More recently, for larger organizations where it takes a longer time for Slack to be adopted across the organization, it’s become a bridge to email. I don’t need to know whether you, an employee I’ve never spoken to before but for whom I have a question, I don’t need to know whether you’re using Slack. I can send you a DM or mention you in a channel and it’ll show up for you as an email, and then you reply and it shows up for me as a Slack. But because the email address ties those people together, when you later join Slack, all those messages that you sent via email are actually Slack messages and are available in your history. The plug-ins are more like, select an email and send to Slack. Often, if I get an email from a customer, I would send that into Slack so that one of the sales leaders or customer success managers and account executives can all see it and have that discussion. It’s better to do it in Slack than to have that discussion over email.

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