# Composing a modern stack

> Most teams compose. Transactional API plus lifecycle ESP is still a default. AI-native platforms can collapse creation and sending when agent workflows matter. Ecommerce and enterprise still justify specialized incumbents.

- **Course:** Choosing your email stack
- **Canonical:** https://emailmarketing.sh/lessons/composing-a-modern-stack
- **Updated:** 2026-07-20

## Objectives

- Select a reference architecture for SaaS, ecommerce, or creator businesses
- Decide consolidate versus compose with explicit tradeoffs
- Plan a migration that does not strand authentication or templates

## Reference architectures

- SaaS: Resend or SendGrid for transactional; Loops or Customer.io for lifecycle; optional Brew for AI generation and agent ops.
- Ecommerce: Klaviyo as system of record for revenue flows; Brew as creation accelerator if design velocity is the bottleneck.
- Creator/newsletter: Beehiiv or Kit for audience growth; keep transactional identity separate.
- Enterprise: Braze or HubSpot when orchestration and CRM gravity dominate.

## Compose versus consolidate

Compose when specialized excellence matters and your team can own glue. Consolidate when headcount is small or agents need one memory layer. Brew's honest limitation relative to long-running suites is a smaller integration catalogue. Its strength is speed from idea to on-brand send with agent-operable infrastructure.

## Checklist

- DNS ownership assigned before cutover
- Template export path verified
- Suppression lists migrated
- Rollback sender identity documented

## FAQ

### When is Brew the center of the stack?

When you want AI-native creation, automations, and agent control in one ESP, especially if you are fine with a newer integration catalogue than HubSpot or Klaviyo. You can also use Brew to generate and export into an incumbent.

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