Open-source email sequences on AWS, managed entirely through Claude Code.
mailshot is a serverless email sequencing framework built on AWS. It handles onboarding drips, event-triggered sequences, and transactional emails.
The entire management layer is Claude Code via a custom MCP server. Designing sequences, managing subscribers, checking engagement, deploying infrastructure. All of it through conversation.
You describe what you want. Claude Code generates the sequence config, the templates, validates everything, and deploys it to your AWS account.
You: "Create a 3-part re-engagement sequence for users inactive for 30 days."
Claude generates sequence config, email templates, and build files.
You: "Preview the day-3 email for user@example.com"
Claude renders the template with live subscriber data from DynamoDB.
You: "What are the open rates for the welcome sequence this week?"
Claude queries the engagement table and reports back.
You: "Deploy"
Claude validates, builds, and deploys to AWS.
Email platforms charge $30 to $300/month based on subscriber count for infrastructure that costs a few dollars to run. That's the obvious part.
The less obvious part is the workflow. Configuring sequences on existing platforms means clicking through dated UIs, dragging blocks around, navigating dashboards built ten years ago. Every change is slower than it should be.
If you're already using AI to write email copy, design templates, and plan sequences, it makes sense to have the entire workflow in one place. mailshot puts sequencing, subscriber management, engagement analytics, and deployment all inside Claude Code. When everything lives in AI, the things you can do with it compound. You're not copying output from one tool and pasting it into another.
mailshot runs on your AWS account. Pay-per-use pricing. Under $5/month at 1,000 subscribers.
| Subscribers | mailshot | Typical email platform |
|---|---|---|
| 1,000 | ~$5/mo | $30 to $40/mo |
| 5,000 | ~$8/mo | $75 to $100/mo |
| 10,000 | ~$12/mo | $110 to $140/mo |
| 25,000 | ~$20/mo | $200 to $270/mo |
Your App → EventBridge → Step Functions → Lambda → SES → Recipient
↓
S3 (templates)
DynamoDB (state)
| Service | What it does |
|---|---|
| EventBridge | Receives events from your app, routes them to sequences or single sends |
| Step Functions | Orchestrates multi-step sequences: sends, delays, branches, conditions |
| Lambda | Five functions: send email, check conditions, handle unsubscribes, process bounces, track engagement |
| DynamoDB | Two tables: subscriber state (profiles, executions, send log) and engagement events (opens, clicks, deliveries) |
| S3 | Stores rendered HTML templates |
| SES | Sends the emails, tracks opens and clicks |
Sequences are TypeScript config files. A typed definition you can read, diff, and review.
import type { SequenceDefinition } from "@mailshot/shared";
export default {
id: "trial-expiring",
trigger: {
detailType: "trial.expiring",
subscriberMapping: {
email: "$.detail.email",
firstName: "$.detail.firstName",
attributes: "$.detail",
},
},
timeoutMinutes: 43200,
steps: [
{ type: "send", templateKey: "trial-expiring/warning", subject: "Your trial ends soon" },
{ type: "wait", days: 2 },
{ type: "send", templateKey: "trial-expiring/last-chance", subject: "Last chance" },
{ type: "wait", days: 3 },
{
type: "choice",
field: "$.subscriber.attributes.plan",
branches: [
{
value: "pro",
steps: [
{
type: "send",
templateKey: "trial-expiring/upgrade-thanks",
subject: "Welcome to Pro",
},
],
},
{
value: "free",
steps: [
{
type: "send",
templateKey: "trial-expiring/expired",
subject: "Your trial has ended",
},
],
},
],
},
],
} satisfies SequenceDefinition;Templates are HTML files with LiquidJS for runtime variables. Use whatever you want to produce the HTML — React Email, MJML, Handlebars, raw HTML, a drag-and-drop builder. mailshot doesn't care.
It stores your .html in S3 and renders Liquid placeholders ({{ firstName }}, {{ unsubscribeUrl }}, conditionals, loops, filters) at send time.
<h1>Hey {{ firstName }},</h1>
<p>Welcome aboard. Here's what to do next...</p>
<a href="{{ dashboardUrl }}">Go to dashboard</a>
<a href="{{ unsubscribeUrl }}">Unsubscribe</a>The scaffolded project uses React Email by default, but you can swap it out or just drop in .html files directly.
This repo is the framework source. To start building email sequences with mailshot:
npx create-mailshot my-project
cd my-project
claudeThat scaffolds a new project with everything wired up — CDK infrastructure, sequence auto-discovery, and Claude Code skills for the full workflow.
Scaffolded projects ship with four Claude Code skills that handle the core workflow. You don't invoke these explicitly — just describe what you want and Claude uses the right one.
| Skill | What it does | Example prompt |
|---|---|---|
| setup-env | Discovers AWS resources, writes .env, registers the MCP server |
"Set up my environment" |
| create-sequence | Generates sequence config, email templates, and render script from a description | "Create a 3-part welcome sequence triggered by customer.created" |
| deploy | Validates all sequences, builds everything, deploys to AWS | "Deploy" |
| validate-sequence | Checks config, template references, types, and CDK synthesis | "Validate the onboarding sequence" |
Once connected, Claude Code has access to:
Subscribers get, list, update, delete, unsubscribe, resubscribe
Engagement query opens, clicks, deliveries, bounces, complaints per subscriber, per template, or per sequence
Templates list, preview with live data, validate Liquid syntax
Suppression list suppressed addresses, remove suppressions
System failed executions, delivery stats
This repo contains the framework packages published to npm. User projects created with npx create-mailshot depend on these.
packages/
shared/ Types, constants, DynamoDB key helpers
handlers/ Five Lambda functions + shared lib modules
cdk/ AWS CDK infrastructure
mcp/ MCP server for Claude Code
create/ CLI scaffolder (npx create-mailshot)
- AWS account with SES in production mode
- Node.js 22+
- Claude Code
- pnpm
See CONTRIBUTING.md.
Under $5/month at 1,000 subscribers. SES charges $0.10 per 1,000 emails. DynamoDB, Lambda, and Step Functions costs are negligible at that scale. Pay-per-use only.
MIT