How Slack Builds Smart Notification Systems Users Actually Want

Table of Contents

• How Slack Designs Notifications to Manage User Attention
• How Slack Reduced Support Tickets with Smarter Notification Design
• Why Smart Defaults Are Crucial for Notification UX
• How Slack Gives Users Control with Notification Preferences
• How Slack's Flowchart Powers Smarter Notification Delivery
• Design Notifications for Long-Term Engagement, Not Growth Hacks
• FAQs

How Slack Designs Notifications to Manage User Attention

Slack's notification system serves over 42 million daily active users by balancing smart defaults with user control. Former Slack product lead and current Adverb Ventures investor Liza Gurtin reveals how her team built notification intelligence that reduces support tickets while increasing engagement. Learn how platforms like Courier enable businesses to implement Slack-level notification sophistication without custom infrastructure.

For companies seeking notification best practices, Slack's approach offers proven strategies for managing user attention, reducing notification fatigue, and building trust through intelligent message routing. This guide examines Slack's notification decision engine, smart defaults strategy, and context-aware controls that create user experiences worth emulating. The challenge of managing attention has never been more critical. Too many notifications transform a productivity tool into a source of constant interruption. Too few, and important conversations slip through the cracks.

For companies looking to implement similar notification sophistication, platforms like Courier.com provide the infrastructure to build Slack-level notification systems without starting from scratch. Courier's multi-channel orchestration allows teams to implement the same intelligent routing that makes Slack's notifications so effective, whether you're sending alerts through Slack channels, Microsoft Teams, email, or push notifications.

Liza Gurtin, who led Slack's notifications team during a pivotal growth period, understood that notifications aren't just features; they're the primary interface between users and the value your product delivers. Her team's approach offers a masterclass in notification design that remains relevant today as businesses navigate an increasingly complex communication landscape.

Watch Liza Gurtin, former product lead at Slack, and Tommy Dang, former Airbnb Engineer and Founder of Mage, discuss notification strategy.

How Slack Reduced Support Tickets with Smarter Notification Design

Notifications have always been core to using Slack. It makes perfect sense: as a messaging app, Slack is only as valuable as the conversations that it enables you to have. And notifications are the primary way that Slack pulls you into these conversations.

But it wasn't until five years after the app launched that a team dedicated to notifications was formed. When Liza took charge of notifications in late 2018, she brought together a team of 10 full-time engineers along with part-time support from design, analytics, and user research.

One of the driving forces behind the new team? A slew of support tickets from frustrated users. "When the team first got started, notifications were actually one of the biggest drivers of support tickets," Liza explains, "and one of the bigger problem areas in the product. In a lot of cases, notifications were working exactly as expected, but they weren't meeting user expectations. Users would complain about missing notifications or being overwhelmed by too many of them."

These support tickets directly informed the team's charter – and their commitment to delivering what Liza saw as the core value of notifications. "Notifications are the primary way that products communicate with their customers, both in and outside the app," Liza says, "and they're deeply entangled with how products manage their users' attention. As the notifications team, that was our charter: to enable Slack users to sort the signal from the noise."

Once formalized, the team's charter led them to prioritize where most problems with notifications start: the default state. That is, before any customization, what notifications should Slack send? This approach to smart defaults is now available to any development team through platforms like Courier, which enables sophisticated notification logic without custom infrastructure.

Why Smart Defaults Are Crucial for Notification UX

One of the most striking insights from Slack's notification strategy is that less than 5% of users ever customize their notification settings. This statistic should be sobering for any product team: your default settings ARE the experience for the vast majority of your users.

"Most users expect your notifications to work exactly the way they want without having to do anything themselves," Gurtin explains. This expectation places enormous responsibility on product teams to nail the out-of-the-box experience.

Slack's approach to smart defaults demonstrates sophisticated thinking about user context:

Desktop-First During Work Hours: When a user is active on their desktop client, Slack suppresses mobile push notifications. This prevents the annoying double-ping that plagues many multi-device experiences.

Email Sunset After Mobile Install: Once a user downloads the mobile app, email notifications automatically turn off. This decision recognizes that push notifications provide more immediate value than email for time-sensitive messages.

Weekend and After-Hours Protection: Slack's Do Not Disturb defaults respect traditional work boundaries while allowing for override capabilities when genuinely urgent matters arise.

These defaults work because they mirror natural work patterns. They anticipate user needs rather than forcing users to configure the system to match their workflow.

Building Trust Through Notification Design

Trust forms the foundation of any successful notification system. Users need confidence in two fundamental promises: they'll be notified when something important happens, and they won't be bothered by trivial updates.

When Gurtin's team took ownership of notifications in late 2018, they inherited a significant trust deficit. Notifications were one of the biggest drivers of support tickets, with users complaining about both missing important messages and being overwhelmed by noise. The problem wasn't technical; the system worked as designed. The issue was that the design didn't match user expectations.

The solution required rethinking notifications from first principles. Instead of asking "When should we notify?" the team began asking "When does the user want their attention drawn to Slack?" This subtle shift in perspective transformed their approach from product-centric to user-centric.

For modern teams building notification systems, tools like Courier's direct message capabilities for Slack enable this same user-centric approach. By providing granular control over notification routing and timing, platforms can respect user attention while ensuring critical messages get through.

The Anatomy of Slack's Notification Decision Engine

Perhaps no artifact better captures the complexity of modern notification systems than Slack's famous notification flowchart. This intricate decision tree, which went viral on social media in 2017, reveals the dozens of factors that determine whether and how a notification reaches a user.

The flowchart evaluates multiple dimensions:

User State: Is the user active, away, or in Do Not Disturb mode?

Message Context: Is this a direct message, a mention, or activity in a subscribed channel?

Device Availability: Which devices are currently active, and what's their priority order?

Time Context: Is this during work hours, after hours, or on a weekend?

User Preferences: Has the user customized any settings that override defaults?

Each branch in the flowchart represents a deliberate product decision about what deserves user attention. The complexity isn't accidental; it reflects the nuanced reality of modern workplace communication.

Implementing Context-Aware Controls

While smart defaults serve the majority, power users need granular control. Slack's innovation wasn't just providing these controls but presenting them at the moment they become relevant.

"Control in context is about presenting users with an opportunity to adjust their notification settings at the exact moment those settings are relevant," Gurtin explains.

Examples of context-aware controls include:

Weekend Interruption Prompts: The first time a user receives a weekend notification, Slack asks whether they want to continue receiving notifications during non-work hours.

Channel Activity Alerts: When a channel generates excessive notifications, Slack surfaces muting options directly in the notification itself.

Mention Frequency Management: Users who receive frequent @mentions see options to adjust mention sensitivity without navigating to settings.

This approach dramatically increases setting adoption rates. Users are far more likely to adjust a setting when experiencing its effects than to proactively hunt through preference menus. Modern notification platforms like Courier enable similar context-aware controls through their preference management system.

Why Growth Hacking Through Notifications Backfires

There's a seductive logic to aggressive notification strategies: more notifications equal more engagement. Gurtin warns against this thinking, calling it one of the most dangerous misconceptions in product development.

"More usage is not always better usage," she cautions. "You might see a big early benefit from sending a lot of notifications. But there's a real downside: if you overwhelm users and they unsubscribe at the system level, at that point, you won't be able to resurrect them at all."

The danger is particularly acute in 2025's notification landscape. Operating systems have become increasingly aggressive about protecting user attention. iOS and Android now provide one-tap notification blocking, and users have become quick to use these nuclear options when apps abuse their attention.

Instead of growth hacking, Gurtin advocates for value-first notification design. She shares an example of a feature her team considered: alerting users to high activity in channels they haven't joined. While this could drive engagement metrics, the team focused on whether joining these channels would genuinely benefit users, not just boost usage numbers. This user-first philosophy is built into Courier's notification platform design principles.

Building Your Own Slack-Level Notification System

Creating a notification system with Slack's sophistication might seem daunting, but modern infrastructure platforms make it achievable for teams of any size. The key is choosing the right foundation.

Platforms like Courier provide the building blocks necessary for sophisticated notification orchestration:

Multi-Channel Routing: Automatically route messages to the most appropriate channel based on urgency, user preference, and context. Whether you're sending Slack and Microsoft Teams notifications or traditional email and SMS, the routing logic remains consistent.

Preference Management: Give users control over their notification experience with built-in preference centers that respect their choices across all channels.

Template Management: Maintain consistent messaging across channels while optimizing each notification for its delivery medium using Courier's template designer.

Analytics and Optimization: Track engagement rates, unsubscribe patterns, and delivery success to continuously improve your notification strategy using Courier's analytics dashboard.

Workflow Orchestration: Build complex notification flows that mirror Slack's sophisticated decision tree without maintaining custom infrastructure using Courier's automation workflows.

Build Your Notification System with Courier

The goal isn't to copy Slack's exact implementation but to adopt their user-centric philosophy. Start with smart defaults that respect user attention. Provide granular controls for power users. And always prioritize long-term trust over short-term engagement metrics.

Courier's notification platform enables teams to implement Slack-level notification intelligence without building custom infrastructure. From multi-channel routing to preference management, Courier provides the building blocks for sophisticated notification systems that respect user attention while driving genuine engagement.

FAQs

How does Slack determine which device receives a notification?

Slack uses a priority system based on user activity and device state. Desktop clients receive priority when active, followed by mobile devices when the desktop is idle. The system prevents duplicate notifications across devices by checking device activity in real-time before sending alerts.

What makes Slack's notification flowchart so complex?

The complexity reflects the nuanced nature of workplace communication. Each decision point in the flowchart represents a different user context or preference that affects notification delivery. Factors include user availability, message urgency, time of day, device state, and custom preferences. This complexity ensures notifications reach users when needed without creating unnecessary interruptions.

How can I implement smart notification defaults in my application?

Start by analyzing your users' typical interaction patterns. Identify peak usage times, preferred devices, and communication urgency levels. Use this data to set defaults that match natural user behavior. Tools like Courier's notification platform provide pre-built intelligence for common patterns while allowing customization for your specific use case.

Why do most users never customize notification settings?

Users expect software to work correctly out of the box. Customizing settings requires understanding the system, predicting future needs, and investing time in configuration. Most users won't make this investment unless the default experience is problematic. This makes smart defaults crucial for user satisfaction.

How can context-aware controls improve notification adoption?

Context-aware controls present options when they're most relevant and understandable. A user receiving their first weekend notification immediately understands the value of Do Not Disturb settings. This timely presentation increases the likelihood of engagement compared to buried menu options that users must discover independently.

What's the difference between notification routing and notification preferences?

Notification routing determines HOW a message reaches a user (which channel, what timing, what format). Preferences determine WHAT messages a user wants to receive. Modern notification systems like Courier handle both: routing ensures optimal delivery while preferences respect user choices about content.

How can I measure notification effectiveness without being invasive?

Focus on outcome metrics rather than engagement metrics. Track support tickets related to missed or excessive notifications. Monitor system-level unsubscribe rates. Measure whether notifications drive meaningful actions, not just app opens. Quality matters more than quantity in building long-term user trust.

Ready to build a notification system that respects user attention while driving genuine engagement? Talk to a Courier solutions architect about implementing Slack-level notification intelligence in your application.