Why PostHog?

PostHog is great. It just doesn't do lifecycle emails.

If you're reading this, you probably already love PostHog. You've got event tracking, feature flags, session replays, A/B testing, and a data warehouse — all in one platform, self-hostable, with a generous free tier. It's the analytics stack startups actually want to use.

But there's a gap. PostHog tells you what users do. It doesn't help you respond to what they do. When someone signs up and doesn't activate, when a payment fails, when a power user goes quiet — you're on your own. You either hand-roll email logic in your app code, or you buy a separate lifecycle platform and spend weeks wiring it up.

Hogsend fills that gap. It listens to your PostHog events and reacts to them with durable, code-first journeys that send emails, check conditions, wait, and branch — all without touching your application code.

Want to see it instead of read about it? pnpm dlx create-hogsend@latest my-app scaffolds a running app, and pnpm bootstrap brings up the full stack for you. See Installation.

PostHog is building this themselves

We should be upfront about this: PostHog acquired the Laudspeaker team in 2025 to build marketing automation into PostHog natively. PostHog Workflows is already a thing, and we expect lifecycle email to land eventually.

We're rooting for them. When PostHog ships their own lifecycle automation, it'll be deeply integrated with their analytics, feature flags, and experimentation platform in ways no external tool can match.

Until then, Hogsend exists. And it's designed with that future in mind:

• Clean event model — Hogsend uses your PostHog events directly. No proprietary event format. When PostHog ships their own tool, your events are already in the right shape.
• Durable fan-out to PostHog — email engagement (email.sent, email.delivered, email.opened, email.clicked, email.bounced, email.complained) fans out to PostHog as a destination on Hogsend's durable webhook spine, with retries and a dead-letter queue. You can build cohorts like "users who opened the welcome email but haven't used feature X" — email engagement alongside product metrics, in PostHog where it belongs. PostHog is one subscriber among many here: Segment, Slack, a CRM, or a warehouse can receive the exact same stream.
• No lock-in — journeys are TypeScript files in your repo. Templates are React components. Data lives in your Postgres. Nothing is trapped in a proprietary format.
• Gateway drug — if you outgrow Hogsend before PostHog ships their solution, you can migrate to Customer.io, Brevo, or any other platform. Your event model and journey logic translate directly.

What PostHog gives Hogsend

Hogsend uses PostHog in three directions, and they're asymmetric: events flow in as journey triggers, person properties are pulled to enrich decisions and resolve timezones, and engagement flows back out to PostHog as one destination among many — not through a privileged PostHog-only pipe.

Events flow in

Every PostHog event can trigger a Hogsend journey. Set up the webhook once (about 2 minutes) and your entire PostHog event stream is available:

• user_signed_up → welcome sequence
• feature_used → activation branching
• subscription_cancelled → churn recovery
• Custom events from PostHog Actions → any journey you define

PostHog forwards each event to POST /v1/events, the same data-plane endpoint your own app code can call. Hogsend stores the event, routes it to any journey whose trigger.event matches, and upserts the contact. See PostHog Webhook Setup for the wiring.

Person properties enrich journeys

Hogsend pulls PostHog person properties (with Redis caching) so your journeys and timezone logic can use the full user profile. The provider is exposed as getPostHog(), which returns undefined when POSTHOG_API_KEY isn't set — so guard it:

import { getPostHog } from "@hogsend/engine";

// getPostHog() returns undefined when POSTHOG_API_KEY isn't set, so guard it.
const properties = await getPostHog()?.getPersonProperties(user.id);
// { plan: "pro", company_size: 50, signup_source: "Product Hunt" }

Engagement flows back out

When Hogsend sends an email and the user opens it, clicks a link, bounces, complains, or unsubscribes — those events fan out to PostHog as a kind="posthog" destination on the durable webhook spine. Set ENABLE_POSTHOG_DESTINATION=true (with POSTHOG_API_KEY set) to auto-seed one. This is the same delivery path any other subscriber uses, so PostHog gets the full email funnel — durably, with retries and a dead-letter queue — and so could Segment or Slack. This means in PostHog you can:

• Cohort building — "users who received the trial-expiring email and clicked through" is a PostHog cohort, not a separate tool
• Funnel analysis — email engagement becomes part of your product funnels in PostHog
• Feature flag targeting — target users based on email engagement using PostHog feature flags
• Session replays — see what a user did after clicking through from an email

If PostHog is the only place you analyze, it can be the single source of truth for both product behavior and lifecycle email engagement — but it earns that role as a first-class destination, not as a hard dependency baked into the engine.

Hogsend is the thing you'd build anyway

Every PostHog team eventually needs lifecycle emails. The question is whether you spend 2-3 weeks hand-rolling it in your app (and maintaining it forever), 6 weeks integrating Customer.io (and paying $500+/month), or 10 minutes setting up Hogsend.

Hogsend is opinionated. It assumes PostHog is your analytics platform and sends email through a swappable provider — Resend by default. It doesn't try to be everything — it just does lifecycle email really well, with the assumption that PostHog is where you want engagement flowing back.

Getting there is one command. pnpm dlx create-hogsend@latest my-app scaffolds a thin app that pins @hogsend/engine and holds your content; pnpm bootstrap then checks Docker, writes .env with a fresh BETTER_AUTH_SECRET, brings up Postgres + Redis + hatchet-lite, auto-mints your Hatchet token, runs the migrations, and mints an ingest-scoped data-plane key — all into .env. Set RESEND_API_KEY before sending real email, point your PostHog webhook at the app, and your event stream starts driving journeys.

When you're ready for more — push notifications, SMS, in-app messages, or PostHog's own marketing automation — you'll have a clean event model, proven journey logic, and engagement data already in PostHog to build on.

Next steps