Slack or Teams: pick one, set it up right

We regularly walk into offices running both Slack and Teams. Half the company chats in one, half in the other, and the two halves communicate by email, which is the thing chat was supposed to replace. Running both is the worst possible answer. It doubles the places a message can hide, doubles the notification noise, and you are probably paying for one of them twice.

So pick one. Here is how we call it, and how to set up whichever one you pick so it does not turn into a second inbox.

The deciding question: do you pay for Microsoft 365?

If your company is on Microsoft 365 Business Basic, Standard, or Premium, you already own Teams. Not a trial, not a lite version: the full product, included in what you are already paying every month. For most small businesses that ends the debate. Paid Slack runs somewhere around eight to fifteen dollars per user per month depending on plan. For a 30-person company that is several thousand dollars a year for a tool that duplicates one you own.

Teams also does things Slack does not do out of the box: it is your phone system if you add Teams Phone, its meetings replace a Zoom subscription, and files shared in a channel land in SharePoint where your permissions and retention already apply.

When does Slack win anyway? A few honest cases. Your company lives in Google Workspace, so the "you already own Teams" argument disappears. You work daily with outside contractors and agencies, where Slack Connect is genuinely smoother than Teams guest access. Or your team is heavily technical and lives on integrations, where Slack's app ecosystem is still deeper. Those are real reasons. "Slack feels nicer" is also real, but it is rarely worth thousands a year plus a second Microsoft bill.

Whichever way you go, set a shutdown date for the loser. Announce it, export what needs keeping, and turn it off. A tool that is "still around for some teams" is not retired, it is a message black hole.

Channel structure: fewer, named predictably

The setup mistakes are the same in both tools, so the fixes are too.

Create channels for ongoing streams of work, not for every topic that comes up. A 25-person company needs maybe ten to fifteen channels, not sixty. A workable starter set:

• announcements: posting restricted to owners. Company-wide, low volume, everyone reads it.
• One channel per team: sales, ops, accounting.
• One channel per major client or project, with a prefix so they sort together: proj-acme-buildout.
• One social channel. Just one.

Write the naming convention down and appoint one or two people who can create channels. In Teams, team owners control channel creation; in Slack you can restrict channel creation to admins in the workspace settings. Open channel creation is how you end up with random2, random-actually, and memes-new.

The other structural rule: work talk goes in channels, not direct messages. A decision made in a DM is invisible to the rest of the team and gone when someone leaves. DMs are for actual one-on-one matters. This is a culture rule, not a setting, and it is worth saying out loud when you launch.

Notification hygiene: the part everyone skips

Chat tools fail when people mute everything because everything pings them. The defaults are too noisy in both products, so fix them on day one and show your team how.

In Teams: Settings, then Notifications and activity. Set channel notifications so that only mentions and replies alert you, not all activity. Then, per channel, use "Channel notifications" on channels you actually need to watch closely. Turn off email notifications for missed activity entirely; you do not need Teams forwarding itself to Outlook.

In Slack: Preferences, then Notifications. Set the global default to "Direct messages, mentions and keywords." Mute high-traffic channels you only need to skim, and star the handful you genuinely follow.

Two etiquette rules make the settings work. First, @channel and @team mentions are for things that genuinely need everyone right now, which is almost nothing. Second, use threads for replies so one conversation does not generate forty channel-level notifications. Also set quiet hours (both tools support them) so a 9pm message does not buzz anyone's phone. If something is truly urgent after hours, that is what phone calls are for.

How you know it is set up right

A month in, look for these signs. Internal email volume drops noticeably; if it has not, people do not trust the new tool yet. Nobody has more than a couple of muted-and-abandoned channels. A new hire can read the channel list and know where everything goes without a tour. And there is exactly one chat tool on everyone's taskbar. That last one is the whole game. The best chat platform is the one all of your people are actually in.