day3
Overview
Description from the maker (original English)
Draft email campaigns in day3 from Claude Code, Cursor or VS Code as editable composer blocks.
PopNx MCP’s three pillars
These three are never merged into one score: opinions, measurements and popularity are different things.
- User voiceiNo reviews yetReviews open together with accounts in a later step
- Our basic checksi3 of 3 passedChecked from public information; code not scanned yet
- UsageiVery new★ –
What you can do with it
We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.
- Connection: Runs in the cloud
- Transport: Streamable HTTP
- Category: Marketing & social media
- You need to fill in: Authorization
Install
Pick the AI app you use, then copy the settings.
Before you install
- Basic checks: 3 of 3 passed
- Runs on the maker’s server: what you ask it goes through their server.
- You fill in yourself:
Authorization
Values marked secret are keys to your account. Never share them or paste them into a chat.
You need
- Runs in the cloudNothing to install; it connects over the internet
Which app do you use?
Pick your app above. We remember it, so next time the button says “Install in …”.
This address needs a key in a request header, which the add-connector menu cannot set. Use Claude Code, Cursor or VS Code instead.
Run this in your terminal
claude mcp add --transport http day3 https://go.day3.app/api/mcp --header 'Authorization: your-value'Fill in the empty values before running it.
Or copy the settings yourself
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"day3": {
"url": "https://go.day3.app/api/mcp",
"headers": {
"Authorization": "your-value"
}
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
Or copy the settings yourself
Paste into .vscode/mcp.json in your project
{
"servers": {
"day3": {
"type": "http",
"url": "https://go.day3.app/api/mcp",
"headers": {
"Authorization": "your-value"
}
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
This address needs a key in a request header, which the add-connector menu cannot set. Use Claude Code, Cursor or VS Code instead.
Your choice stays on this device in a cookie; no account needed.
Values you fill in
Authorizationsecret required HTTP headerBearer token: 'Bearer day3_live_...', an API key created in the day3 app
These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.
What it can do
The server asks you to sign in before it lists its tools.
Basic checksi
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 10, 2026
- ✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account Mopra, which owns the repo
- … Not checked yet
Still maintained
We have not read this repo from GitHub yet
- … Not checked yet
Has a licence
We have not read this repo from GitHub yet
- ✓ Pass
Endpoint responds
Responded in 626 ms (HTTP 401)
- ✓ Pass
Sign-in with OAuth
Declares OAuth sign-in, so your AI app can take you to log in
- … Not checked yet
No hidden instructions in tool descriptions
Not checked yet; we read the tool list when we check the endpoint
Compared with others in Marketing & social mediai
- More stars than 0% of the other 3717 servers in this category
- Published to the registry more recently than 50% of the other 3717 servers in this category
- Basic checks equal to or better than 100% of the other 3717 servers in this category
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
Common questions
Is day3 safe?
It passed 3 of 3 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
What keys or codes does it need?
You need to fill in: Authorization
Does it run on my computer or in the cloud?
It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.
Is it still maintained?
The GitHub repo last changed –, and the latest version (1.0.0) reached the registry 29 days ago.
Which apps can use it?
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.
What can I use instead?
In the same category: MCP YouTube Transcript, Google Analytics MCP, BibiGPT YouTube Video Summarizer
Alternatives
Servers in the same category from other makers, sorted by stars.
Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
Google Analytics MCP
GA4 MCP server for AI agents: schema discovery, server-side aggregation, analysis-ready defaults.
BibiGPT YouTube Video Summarizer
AI video summarizer: summarize and transcribe YouTube, Bilibili, TikTok and podcast videos.
README from the maker
Open the README
Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.
Day3
Marketing and transactional email, billed by sends. $1/mo. No contact tax, no marketing suite to learn.
[day3.app](https://day3.app)
Source-available, not open source. This code is published for
transparency and reference. See LICENSE for terms.
This repository is the Day3 product itself: the app at go.day3.app, the public REST API, the webhook and MCP endpoints, and the worker that sends the mail.
What it does
Day3 is a deliberately small email tool for small SaaS teams. Send product updates and changelogs to your users, and send your app's transactional email (password resets, receipts, magic links), through one verified domain, one monthly allowance, and one place to see delivery.
- Campaigns with a block composer, optional AI assist, scheduling, and per-send stats
- Audiences with segments (saved filters), topics (subscription categories), CSV import, and hosted signup forms
- Transactional email over
POST /v1/emails, Resend-compatible in shape, with per-email delivery status - Automations: onboarding and lifecycle flows drawn on a node canvas, published as immutable versions, unlimited on every tier
- Deliverability by default: verified sending domains, double opt-in, one-click unsubscribe, automatic bounce and complaint suppression, account auto-pause on bad reputation
- Metrics for deliverability, reputation and engagement, plus a searchable log of every email you ever sent
- Public API v1, signed webhooks, and an MCP server so Claude Code, Cursor or VS Code can draft a campaign that lands in Day3 as editable blocks
- Billed on sends, not subscribers. Free accounts set up domains, build audiences and send for real in sandbox mode. Paid plans buy the allowance to reach everyone else.
PRODUCT.md is the canonical description of what Day3 is, what it costs, and how every feature behaves. Read it before the code.
Tech stack
| Layer | Technology |
|---|---|
| Web framework | Next.js 16 (App Router) on Vercel |
| UI | React 19, Tailwind CSS 4, shadcn/ui on Base UI, react-hook-form, Zod |
| Rich text | TipTap |
| Database | Postgres (Supabase) via Drizzle ORM, postgres.js driver |
| Queue / jobs | BullMQ + Redis (ioredis), drained by the VPS worker |
AWS SES v2 (eu-north-1) for sending, AWS SNS for delivery events | |
| Auth / tenancy / billing | Clerk (Organizations are the tenant boundary, plus Clerk Billing) |
| File storage | Supabase Storage (CSV imports) |
| AI (optional) | OpenRouter via the Vercel AI SDK |
| MCP server | Hand-rolled JSON-RPC over Streamable HTTP at /api/mcp, stateless and tools-only |
| DNS automation | Cloudflare OAuth, optional, for auto-configuring SES records |
| Testing | Vitest with pglite, an in-memory Postgres per test |
Quick Links
| Website | day3.app: what Day3 is, pricing, and the case for it | Repo |
| App | go.day3.app: sign in, write campaigns, send email | Repo |
| Documentation | docs.day3.app: API reference, guides, webhooks, MCP | Repo |
Built by Pradsgaard Labs. Also from the same workshop: exit1.dev, uptime monitoring.
Local development
npm installEnv: web tier + worker (see "Required environment variables" below)
cp .env.example .env.local cp .env.worker.example .env.worker
Database
npm run db:migrate # forward-only, applies un-applied journal entries npm run db:seed # optional sample data
npm run dev # Next.js on http://localhost:3000 npm run worker # BullMQ worker, in a second terminal
Sign in with Clerk and create an organization, and you have a tenant. The campaign pipeline (review, generate recipients, batched queue sends, stats) works end to end locally.
Useful:
npm test: vitest against real Postgres (pglite). Applies migrations from scratch every run and asserts schema, journal and snapshots agree. Idempotency tests live here too.npm run typecheck/npm run lint/npm run buildnpm run db:generate: new Drizzle migration after schema changesnpm run db:studio: browse the local database
Migration discipline
src/db/schema.ts is the single source of truth. SQL under migrations/ is forward-only and generated, never edited by hand. The journal (migrations/meta/_journal.json) and the per-migration *_snapshot.json files are part of the migration, so always commit them together.
Workflow when you change the schema:
- Edit
src/db/schema.ts. npm run db:generatewrites the nextNNNN_*.sql, its snapshot, and the journal entry.- Review the SQL (squash or rename within the same PR if the diff is noisy), then commit the SQL and the
meta/changes in one commit. npm testproves it applies cleanly from scratch.
CI enforces this: it re-runs drizzle-kit generate and fails the build if that produces any diff, meaning schema.ts and the committed migrations disagree or a migration was added without its snapshot. Two contributors who both generate a migration will collide on the next NNNN index. Resolve it by regenerating one off the merged schema.ts so the journal stays linear.
Apply order in production is drizzle-kit migrate (see the deploy checklist), which replays only the un-applied journal entries against DATABASE_URL and records them in the __drizzle_migrations table. Never db:push, which diffs live and can drop columns.
Required environment variables
Both processes validate their environment at startup (src/lib/env.ts) and refuse to boot if a required variable is missing or a secret is too short (min 16 chars). This prevents the empty-key failure mode where an unset UNSUBSCRIBE_SECRET would sign HMAC tokens with "" (forgeable unsubscribe and one-click links) or an unset OAUTH_STATE_SECRET would void OAuth CSRF protection. The Next web tier validates on first server module load (instrumentation.ts). The worker validates in worker/index.ts before it starts consuming.
| Variable | Web | Worker | Notes / generation |
|---|---|---|---|
DATABASE_URL | ✓ | ✓ | Postgres connection string. |
UNSUBSCRIBE_SECRET | ✓ | ✓ | HMAC key for unsubscribe and one-click tokens. MUST match across both tiers. node -e "console.log(require('crypto').randomBytes(32).toString('hex'))" |
OAUTH_STATE_SECRET | ✓ | HMAC key for the Cloudflare OAuth state cookie (CSRF). node -e "console.log(require('crypto').randomBytes(32).toString('hex'))" | |
DNS_TOKEN_ENC_KEY | ✓† | base64 of 32 raw bytes (AES-256) encrypting Cloudflare DNS tokens at rest. node -e "console.log(require('crypto').randomBytes(32).toString('base64'))". †Or DNS_TOKEN_ENC_KEYS + DNS_TOKEN_ENC_ACTIVE_KEY_ID for rotation, see docs/cloudflare-dns-oauth.md. | |
CLERK_WEBHOOK_SIGNING_SECRET | ✓ | Verifies Clerk webhooks. Use a 16-char or longer placeholder locally. | |
AWS_REGION | ✓* | ✓* | *Required only when EMAIL_PROVIDER=ses. |
See .env.example (web) and .env.worker.example (worker) for the full list, including non-secret config: Clerk publishable and secret keys, Redis, Supabase Storage, and SES credentials.
Going to production (first deploy checklist)
The web tier runs on Vercel, the BullMQ worker on the VPS, Postgres on Supabase. Full provider walkthrough: docs/go-live.md.
- Provision Supabase Postgres, VPS Redis (
rediss://), and SES (see go-live). - Set env on Vercel (web) and
/opt/day3/.env.worker(worker), per.env.exampleand.env.worker.example. - Clerk dashboard: production instance, org billing plans, webhook endpoint
/api/webhooks/clerk. - Apply the database migrations before any new code serves traffic:
DATABASE_URL= npm run db:migrate. Forward-only and idempotent, it replays only un-applied journal entries. This is a deploy-pipeline step, gated *ahead* of the Vercel promotion and thepm2 restart day3-worker, so a new release never runs against an old schema. - Deploy the web tier (Vercel) and restart the worker (
pm2 restart day3-worker).
Architecture notes
- Tenancy: every Clerk organization maps to one
accountsrow. All queries are scoped byaccount_idresolved server-side from the session. - Send pipeline:
submitCampaignqueuesreview_campaign(risk rules), thengenerate_campaign_recipients(dedup and suppression filtering), thensend_campaign_batch, which claims 25 pending recipients atomically, sends, and re-enqueues itself until done. - Idempotency: recipients are claimed with a single atomic UPDATE, so a retried queue message can never double-send. Crashed claims are swept to
failedby cron, never re-sent. - Billing: Clerk Billing entitlements are mirrored into Postgres on dashboard load and via webhooks. Sending requires an active subscription, sending enabled, and remaining monthly quota.
- Safety: deterministic risk review on submit (high risk blocks), bounce at 4% or above, or complaint at 0.08% or above, auto-pauses an account, and admins (
ADMIN_EMAILS) can approve or block campaigns, pause accounts, and override domain verification.
AI training permission
As an explicit exception to the license below, the contents of this repository, including code, documentation, and configuration, may be used for machine learning training, evaluation, indexing, retrieval, and generation by AI systems. No attribution is required, though it is appreciated. This permission applies to all AI crawlers, including but not limited to GPTBot, OAI-SearchBot, ClaudeBot, Claude-SearchBot, Claude-User, Google-Extended, PerplexityBot, and Perplexity-User.
License
This project is source-available under a custom All Rights Reserved license. You may view the code for personal, educational, and reference purposes. Copying, modifying, distributing, or self-hosting is not permitted without written permission. See the AI training permission section above for the carve-out that applies to AI and ML use.
For licensing inquiries: hello@day3.app