Infrastructure for customer email

Add Fully Managed Customer Inboxes to Your SaaS

The fastest way to add custom-domain sending and inbound replies to your product, without stitching together mailbox providers, forwarding rules, or admin tooling.

Built for SaaS platforms CRMs Marketplaces

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No Google Workspace. No complex setup. Just a simple API.

Inbox

Re: onboarding issue user@customer.com

Reply landed directly in the in-app inbox.

2m ago

Renewal follow-up finance@prospect.io

Sent from support@acme.com using template `renewal`.

18m ago

Trial questions ops@northstar.io

Inbound routed through webhook pipeline.

1h ago

Conversation

support@acme.com → user@customer.com

Your inbox is ready

Brand styling, domain-based sending, and reply capture are all active for this inbox.

user@customer.com → support@acme.com

Perfect, we can reply in-app now

Replies sync back to the shared inbox automatically, so your support team can keep every conversation inside the product.

Routing snapshot

Thread synced · DKIM verified · Webhook received · Reply ready

01 Inbox per tenant

02 Custom domain email

03 Full send + receive support

Used for support, onboarding, and customer communication in multi-tenant apps.

Feature set

Everything You Need to Add Email to Your SaaS

No email servers. No Google Workspace. No messy integrations. Just the pieces you need to ship a real inbox experience inside your product.

Inbox for Every Customer

Provision an isolated inbox with thread history for every customer account.

Send from Custom Domains

Send from addresses like `support@theircompany.com` with simple DNS setup.

Full Send + Receive Support

Handle outbound email and inbound replies through one API and webhook model.

Branded Email Templates

Apply customer branding automatically so every message feels product-native.

Reliable Delivery Built In

Get routing, retries, and provider failover without running delivery infrastructure yourself.

Mailbox UI idea

Show Prospects What Their In-App Mailbox Could Feel Like

A shared inbox does not need to look bolted on. This concept shows how a tenant-aware mailbox can blend conversation triage, customer context, and reply controls inside one product-native workspace.

Mailbox concept

Built for support, onboarding, and account conversations

128 Open threads

4m Median reply time

99.2% Delivery health

Launch checklist questions 2m

onboarding@northstar.io

Needs product guidance before domain verification goes live.

Invoice routing confirmation 18m

finance@acme.com

Billing reply was sent from the tenant mailbox with branding applied.

Inbound alias setup 41m

ops@luma.app

Webhook event received and mapped to the shared support queue.

Launch checklist questions

Northstar • onboarding@northstar.io

Assigned to Priya SLA healthy

Customer • 9:14 AM

We have DNS ready. Can we verify the sending domain first and then turn on the shared mailbox for onboarding replies?

Priya from support@northstar.io • 9:18 AM

Yes. We usually verify the domain first, then enable routing so replies start landing in the in-app mailbox immediately.

Reply Template suggestions • Snippets • Internal note

Happy to help. Once DNS is green, your team can send from support@northstar.io and keep every reply inside the workspace.

Product spotlight

Email That Lives Inside Your Product

Give your users a fully integrated email experience with inboxes, replies, and branded sending that stay inside the workflows they already use every day.

Tenant isolation

Each inbox maps cleanly to one tenant, keeping activity and permissions separated.

Inbound replies

Replies flow back into the same thread automatically, ready for your app UI.

Domain-based sending

Customers send from their own domain while you manage the infrastructure underneath.

Recent threads

Shipping question retail@customer.co

Inbound reply matched to existing conversation.

Support handoff agent@acme.com

Thread shared with internal operator dashboard.

Domain health

SPF, DKIM, and bounce routing all green for `acme.com`.

Webhook event

`message.received` delivered to `/webhooks/inbound` and synced to tenant inbox.

Template payload

Brand assets, reply-to address, and tenant signature inserted automatically.

Setup flow

How It Works

Go from zero to fully working email in minutes.

Create a tenant

Provision an isolated inbox and mailbox identity for each customer workspace.

Connect a domain

Guide customers through DNS setup once and store a verified sending identity.

Send emails via API

Trigger transactional or conversational messages from one clean endpoint.

Receive replies automatically

Capture inbound events and sync them into your tenant inbox UI in real time.

Use cases

Built for Modern SaaS Applications

SaaS Platforms

Customer-specific communication layered directly into multi-tenant products.

CRMs

Keep conversation history close to contacts, activity logs, and internal workflows.

Marketplaces

Enable buyer and seller messaging without pushing users into external inboxes.

Support Tools

Build shared inboxes and reply handling into the product your teams already use.

API-first

Developer-Friendly by Default

Send email, receive replies, and manage inboxes through one clean API that fits naturally into modern backend systems.

One object model

Tenants, domains, messages, and webhooks all follow the same predictable schema.

Built for backends

Use straightforward JSON requests and webhook events instead of mailbox plumbing.

POST /v1/send

{
  "tenant_id": "acme",
  "from": "support@acme.com",
  "to": "user@customer.com",
  "template": "reply",
  "variables": {
    "agent_name": "Maya",
    "thread_id": "thr_20481"
  }
}

Pricing preview

Simple, Scalable Pricing

Free

For prototypes and early integrations.

3 tenants
1,000 emails/month
Basic inbox support

Growth

$49

For teams shipping customer-facing inboxes.

25 tenants
25,000 emails/month
Custom domains and inbound email

Scale

$199

For production workloads and higher throughput.

100 tenants
100,000 emails/month
Analytics and failover

View Pricing

Start now

Start building with email + inboxes today

Built for developers shipping multi-tenant applications that need real customer communication.

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