Guide

Throttling notifications across product, transactional, and marketing streams

A notification throttle that drops every event over a limit works fine for marketing nurtures and fails for product notifications, because product events carry context users actually need. The fix is pairing throttling with auto-batch: overflow events feed a batch node that rolls them up into a single digest, optionally rewritten by an AI node that prioritizes and summarizes the contents. This guide covers per-stream throttle setups for transactional, product, and marketing flows, and how the Courier Journeys AI node and fetch-data node fit into the pattern.

How to Send Notifications from an AI Agent with Courier's MCP Server

AI agents handle support tickets, monitor pipelines, run onboarding flows, and sync CRM data. When they do, someone needs to know what happened. Courier's MCP server gives agents direct access to the full notification API: send across email, push, SMS, Slack, and in-app. Check user preferences before sending. Trigger batch and digest Journeys so high-volume agents don't spam users. This guide covers MCP server setup, CLI tooling, Courier Skills for your IDE, and five real-world patterns with starter prompts.

Build with AI: let your agent handle notifications end to end

Courier's Build with AI toolkit gives coding agents direct access to your notification infrastructure. Four integration points, one goal: let your agent send messages, debug deliveries, manage users, and follow notification best practices without context-switching. Works with Claude Code, Cursor, and any agent that can run shell commands or call MCP tools.

Expo Push Notifications: The Complete Implementation Guide (SDK 52+)

Expo push notifications are alerts sent from a server to a user's phone, even when the app isn't open. To set them up, install the expo-notifications library, ask the user for permission, and get a unique push token for their device. Your server sends a message to Expo's push service with that token, and Expo delivers it through Apple or Google. Push notifications only work on real phones, not simulators. Local notifications are different — they're scheduled by the app itself for things like reminders. You can also route Expo push through services like Courier to add email, SMS, and Slack fallbacks.

Best Email API Providers for Developers in 2026: SendGrid vs Postmark vs Mailgun vs SES vs Resend

Your email provider sticks with you longer than most technical decisions. Courier handles notification infrastructure for thousands of teams, so we went deep on the six email providers that show up most: SendGrid, Postmark, Mailgun, Amazon SES, Resend, and SMTP. This guide covers real API primitives, actual code from each provider's docs, Courier integration examples with provider overrides, and an honest read on where each developer experience holds up and where it breaks down. We also asked Claude to review every API and tell us which one it would wire up first. The answer surprised us.

What's the Difference Between Omnichannel & Multichannel

Most teams say "omnichannel" when they mean "multichannel," and in most cases the distinction doesn't matter much. But if you truly want to provide an exceptional customer engagement experience you should know the difference. Both involve sending messages across email, push, SMS, Slack, and in-app. They terms diverge when those channels know about each other. Multichannel means you can reach users on multiple channels. Omnichannel means those channels share state, so a user who reads a push notification won't get the same message via email an hour later. This guide breaks down the real distinctions, when the difference actually matters, and which messaging platforms deliver true omnichannel coordination.

A Resilient Notification Strategy for Regulated Industries

Notification compliance isn't a legal checklist—it's an infrastructure problem. In 2026, Reg E deadlines, HIPAA content rules, and TCPA consent requirements dictate your system architecture. This guide breaks down the engineering constraints of regulated notifications for fintech, healthcare, and insurance. Learn why hard-coded deadlines fail, how "alert without disclosing" works in practice, and why the smart escalation pattern (Push → SMS → Email) is the only way to satisfy both user urgency and regulatory documentation. Build systems that absorb complexity, not application code that breaks every time a state law changes.

The Unsubscribe Paradox: Why Making It Easier to Leave Keeps People Around

Hiding the unsubscribe link doesn't keep people subscribed. It makes them mark you as spam, and spam complaints hurt your sender reputation roughly 1000x more than unsubscribes. The brands with the lowest unsubscribe rates don't achieve it by making the door hard to find. They achieve it by making people not want to leave. This guide covers the math behind why easy unsubscribes protect deliverability, how preference centers reduce list churn, and what your unsubscribe flow should actually look like.

Cross-Channel Notification State: Why Read Receipts Are Harder Than They Look

When a user opens your email, does your app know? For most products, the answer is no. Each channel tracks its own state. Email has read receipts. Push has delivery confirmation. In-app has its own unread count. They don't talk to each other. Users notice. This guide covers the three approaches to notification state management (channel-first, central-first, event-first), when to use each, and how to implement cross-channel sync without overengineering. Includes state diagrams and practical implementation patterns.