If you're using Segment, you've already invested in getting your customer data right. Events flow from your app into Segment, get cleaned and routed, and land in the tools that need them. The question is which email tool should be on the receiving end.

The integration quality varies a lot. Some email platforms have native Segment destinations that take five minutes to set up. Others require custom functions or webhook workarounds. And the depth of integration matters too. Receiving events is one thing. Using those events to trigger automations, build segments, and personalize emails is another.

I evaluated these based on how well they actually use Segment data, not just whether they technically connect.

What Makes a Good Segment Integration?

Before the list, here's what to look for:

Native destination: A first-party integration in the Segment catalog (not a custom webhook)
Event mapping: Segment track events map cleanly to the email platform's event model
Identity resolution: Segment identify calls sync user profiles without duplicates
Audience sync: Segment Engage audiences can sync to email lists or segments
Real-time processing: Events trigger emails immediately, not on a delay

The 7 Best Options

1. Sequenzy

Best for: SaaS founders wanting event-driven email without complexity

Sequenzy accepts events via API, making it straightforward to route Segment track events to Sequenzy using a Segment function or webhook destination. When events arrive, they trigger automated sequences (onboarding, dunning, lifecycle emails) without any additional configuration.

The setup works like this: Segment captures events from your app, a destination function forwards relevant events to Sequenzy's event API, and Sequenzy handles the rest. You get lifecycle automation driven by the same events you're already tracking.

Pricing: From $29/month Segment integration: Webhook destination or Segment function Pros: Event-driven automations, lifecycle email for SaaS, Stripe integration, simple setup Cons: No native Segment catalog destination (yet), newer platform

2. Customer.io

Best for: Technical teams wanting the deepest Segment integration

Customer.io has arguably the best Segment integration in the email space. Track events from Segment become Customer.io events automatically. Identify calls create and update customer profiles. You can trigger any automation based on Segment events without any additional code.

The Segment destination supports event filtering, so you can choose exactly which events flow into Customer.io. This matters when you have dozens of event types but only want to trigger emails on a handful of them.

Pricing: From $100/month Segment integration: Native destination (Device Mode + Cloud Mode) Pros: Deepest event integration, full automation support, event filtering, real-time Cons: Expensive, complex setup, overkill for simple email needs

3. Braze

Best for: Enterprise teams with complex multi-channel campaigns

Braze's Segment integration handles both event streaming and audience syncing. Segment track events trigger Braze campaigns and canvases. Engage audiences sync as Braze segments. The integration is battle-tested at scale.

The downside is Braze itself. It's enterprise software with enterprise pricing and enterprise complexity. If you're a startup using Segment, Braze is probably more than you need.

Pricing: Custom (typically $50K+/year) Segment integration: Native destination (Cloud Mode) Pros: Enterprise-grade, multi-channel, audience sync, battle-tested at scale Cons: Very expensive, complex, requires dedicated team to manage

4. Iterable

Best for: Growth teams wanting Segment data for cross-channel campaigns

Iterable's native Segment destination maps events cleanly to Iterable's event model. Track calls trigger workflows, identify calls update user profiles, and group calls manage list membership. The integration supports both cloud mode and device mode.

Iterable is strong on cross-channel (email, push, SMS, in-app), so if you need Segment data feeding into more than just email, it's a solid choice. The pricing is mid-market, which means it's accessible to growth-stage companies but not cheap.

Pricing: Custom (typically $500+/month) Segment integration: Native destination (Cloud Mode + Device Mode) Pros: Cross-channel, clean event mapping, workflow triggers, good documentation Cons: Custom pricing, learning curve, mid-market positioning

5. Loops

Best for: Early-stage startups wanting simple Segment-to-email flow

Loops accepts events via API, and you can route Segment events to Loops using a function destination. Track events trigger Loops automations, and identify calls can create or update contacts. The simplicity of Loops means there's less to configure once events arrive.

The trade-off is depth. Loops automations are simpler than what Customer.io or Iterable offer. For a startup that just needs welcome sequences and basic lifecycle emails triggered by Segment events, that simplicity is actually a feature.

Pricing: Free for 1,000 contacts, from $49/month Segment integration: Webhook destination or Segment function Pros: Simple, good free tier, event-driven model, fast setup Cons: Basic automations, limited segmentation, no native Segment destination

6. Klaviyo

Best for: E-commerce brands using Segment for unified customer data

Klaviyo has a native Segment destination that syncs events, user profiles, and traits. For e-commerce businesses already using Segment to unify their Shopify, ad platform, and analytics data, adding Klaviyo as a destination is easy.

The integration is primarily designed for e-commerce use cases. Segment events like "Order Completed" and "Product Viewed" map naturally to Klaviyo's automation triggers. For SaaS, the fit is less natural since Klaviyo's templates and automations are built around e-commerce workflows.

Pricing: Free up to 250 contacts, from $20/month Segment integration: Native destination (Cloud Mode) Pros: E-commerce focus, native destination, revenue attribution, flow triggers Cons: E-commerce-centric, SaaS fit is awkward, pricing scales with contacts

7. SendGrid

Best for: Developers wanting Segment data for transactional email

SendGrid's Segment integration focuses on syncing contact data and events for marketing campaigns and transactional email. Identify calls update SendGrid contacts, and track events can trigger automations through SendGrid's Marketing Campaigns.

The integration is functional but basic compared to platforms built around events. SendGrid is fundamentally a transactional email service that added marketing features. If your primary need is event-triggered transactional emails, the Segment integration works fine. For complex automations, other options on this list are better suited.

Pricing: Free for 100 emails/day, from $20/month Segment integration: Native destination (Cloud Mode) Pros: Transactional email strength, native destination, generous free tier Cons: Weak automations, marketing features feel bolted on, basic event handling

Setting Up the Segment Integration

Native Destination (Simplest)

For tools with native Segment destinations (Customer.io, Braze, Iterable, Klaviyo, SendGrid):

Go to Segment > Destinations > Add Destination
Search for the email platform
Configure API keys and settings
Choose which events to forward
Enable the destination

Segment Function (For API-Based Tools)

For tools that accept events via API but don't have a native destination (Sequenzy, Loops):

Go to Segment > Functions > Create Function
Write a destination function that maps Segment events to the email platform's API
Handle track events (map to platform events) and identify events (create/update contacts)
Deploy and connect to your sources

This approach gives you full control over event mapping and filtering, which some teams actually prefer over native destinations.

How to Choose

You need the deepest possible Segment integration: Customer.io. The native destination handles every Segment event type and maps cleanly to Customer.io's automation engine.

You're an enterprise team with multi-channel needs: Braze or Iterable. Both have robust Segment integrations and support channels beyond email.

You're a SaaS startup wanting lifecycle email: Sequenzy. Route your Segment events to Sequenzy's API and get onboarding, dunning, and retention automations without enterprise complexity.

You want the simplest possible setup: Loops. Forward Segment events and get basic automations running quickly.

You're in e-commerce: Klaviyo. The Segment integration is built for e-commerce event types.

You primarily need transactional email: SendGrid. Reliable delivery with Segment contact syncing.

FAQ

Does Segment replace the email platform's own event tracking? It can. If you're already tracking events in Segment, there's no need to add the email platform's SDK to your app. Just route Segment events to the email destination. This keeps your instrumentation in one place.

What about Segment Engage audiences? Engage audiences (formerly Personas) can sync to some email platforms as segments or lists. Customer.io, Braze, and Iterable support this. It lets you build audiences in Segment using data from multiple sources and then target them in your email campaigns.

Is there latency when routing events through Segment? Minimal. Cloud mode destinations typically add 1-5 seconds of latency. For most email use cases (onboarding sequences, lifecycle emails), this is imperceptible. For truly time-critical transactional emails (password resets), you might want to call the email API directly.

Can I filter which events go to my email tool? Yes. Both native destinations and Segment functions support event filtering. You should filter aggressively. Your email platform doesn't need every page view and button click. Send only the events that trigger emails or update contact profiles.