Slack vs. Email: The Case for RTC for Enterprise IT

Many organizations are considering the use of Slack vs. email. Here are criteria for evaluating Slack and other real-time communication tools.

Christopher Tozzi, Technology analyst

March 31, 2019

7 Min Read
Slack vs. Email: The Case for RTC for Enterprise IT

Slack, Microsoft Teams, Basecamp and similar real-time communication apps have become critical tools for IT professionals during the past few years. They enable engineers and admins to communicate quickly, and many tools support sophisticated integration with the software systems these professionals maintain. Especially in this age of continuous delivery, many organizations are considering Slack vs. email--or, more generally, real-time communication tools vs. old-school communication technologies like email, phone calls and even face-to-face meetings.

Keep reading for tips on when to use a real-time communication tools and when to stick with an older communication technology. I’ll discuss Slack in particular as an app that is emblematic of the types of tools whose pros and cons I want to weigh, but the lessons below apply generally to all of the real-time communication apps for teams that have emerged in recent years.

What Are Real-Time Communication Tools?

First, though, let me explain what I mean by real-time communication tool.

Tools such as Slack, Microsoft Teams and Basecamp are designed to help members of the same team communicate with each other. These tools vary in scope and functionality, but they all share a few key traits:

  • They enable people to communicate in real time.

  • Access to communication channels inside the tools is limited. You must be a member of a given communication channel in order to participate in it. This makes these tools different from, say, email, which anyone can send to anyone.

  • They support intelligent integrations with IT systems. For example, you could set up an APM tool to send notifications to a Slack channel automatically when it detects a problem.

The Benefits of Real-Time Communication Tools

These tools offer a number of benefits (which is why Slack’s user base has grown from around 16,000 in 2014 to upward of 8 million today). The main ones include:

  • They save users from having to wade through long email lists or threads to participate in conversations.

  • They provide the ability to communicate with individual team members or an entire group easily.

  • You don’t need to keep track of email addresses to connect with a team member; generally, you can quickly find someone by searching for a name.

  • In general, the tools dispense with formalities--like having to write an email subject line, greeting and closing--that can make older communication tools feel inefficient.

To Slack or Not to Slack?

Yet, despite the benefits of Slack and similar communication tools, there are questions you should ask yourself before deciding to use them, including:

1. How many teams do you have, and how large are they?

Tools like Slack are great for sharing information within a team of a limited size--say, a few dozen people or fewer.

They’re not so great when you have a large team, however. Having hundreds of people trying to communicate in the same Slack channel at once is a recipe for information overload.

Likewise, Slack can become unwieldy if you are a member of more than a few teams. It’s hard to keep track of messages for lots of teams at once, and you’re likely to start missing messages.

2. Is real-time communication a priority?

Certain types of information are best communicated in real time. Data and conversations about an application performance or security incident is one example of information you’d want to share instantly.

In contrast, information that doesn’t require instant reaction, or that people might need to reference multiple times in the future, is better shared via an asynchronous communication channel such as email. Not only does email make it easier to find a message again in the future, but it’s also less likely that people will ignore the message if they don’t read it soon after it is sent. If you’re announcing a new company policy or an upcoming event, email is probably a better way to do it.

3. Cost

Most real-time communication tools cost money to use at scale for a business. Pricing for the basic version of Slack starts at $6.67 per user per month, a price that add up quickly.

More traditional communication technologies are less costly. Email is free if you run your own server (although few folks do that these days). Hosted email services like Exchange Online or Gmail cost money, but not as much.

For example, Gmail’s basic $5 per user per month fee beats Slack’s pricing--especially when you consider that with a paid Gmail plan, you get not just email, but also a slew of other business productivity and communication tools/ (This includes real-time chat tools, although they don’t offer the types of integrations with third-party apps that Slack does).

4. App integrations

Speaking of app integrations, they are another core feature that you should consider when deciding whether to use a tool like Slack.

It’s relatively easy to connect a multitude of third-party apps to Slack. But just because you can integrate apps with Slack doesn’t mean you should. Will funneling monitoring alerts into a Slack channel improve response time, or are your engineers already monitoring that data somewhere else? In the latter case, a Slack integration, while cool, is likely to create redundant monitoring output--not to mention burden your engineers with another Slack channel that they’re expected to monitor, even though they probably won’t follow it closely.

5. Log retention, archiving and compliance

Organizations also have to consider the issue of how long communications are stored, and what implications that setting has on compliance policies.

Slack has a pretty sophisticated system for configuring message retention policies. You can automatically remove messages after just one day, if you want, or you could keep them for much longer. Of course, most modern email servers and services offer the same types of retention settings.

What Slack doesn’t do well is automatically archive message data in a way that isolates it from most users, yet keeps it available for reference if needed. This type of data storage policy can be useful in situations where you don’t want messages to sit out in the open forever due to security or privacy concerns, but you also don’t want to remove the messages permanently.

6. Openness and lock-in

Last but not least, consider the ever-present challenge of avoiding lock-in. Slack, Teams and the like are all proprietary tools. It’s anyone’s guess as to whether they’ll still be working five, 10 or 50 years from now, and whether you’ll be able to access data stored in them in the event that they stop working or that you decide to migrate your operations to a different communications platform.

In contrast, if you stick with traditional communication tools like email, you’re less likely to be locked in. Email is already a decades-old technology, and--despite all of email’s shortcomings--it’s hard to imagine email disappearing anytime soon. Plus, email’s data formatting and communication protocols are open and standardized; even if you use a proprietary email server or service, it formats data and sends messages in ways that other email servers can understand.

Thus, not only is email likely to outlive Slack, but even if email does finally die one day, there will almost certainly still be ways to access email messages because there are no secrets regarding how to open or send an email.


Slack and other real-time communication platforms are valuable tools. They have enabled a new level of productivity when certain types of communication are involved. However, they’re not a full replacement for older tools, like email (to say nothing of older-generation chat tools like IRC). If you use Slack or a similar app for the wrong type of use case, it will create confusion and headaches, rather than get rid of them.

About the Author(s)

Christopher Tozzi

Technology analyst, Fixate.IO

Christopher Tozzi is a technology analyst with subject matter expertise in cloud computing, application development, open source software, virtualization, containers and more. He also lectures at a major university in the Albany, New York, area. His book, “For Fun and Profit: A History of the Free and Open Source Software Revolution,” was published by MIT Press.

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