sendstack

An open-source email outbound platform. Built as an attempt to recreate something like Instantly.ai — turns out getting emails to reliably land in inboxes is really hard.

Status: No longer actively maintained.

What it does

• Send email campaigns via any SMTP provider (Zoho, Gmail, G-Suite, etc.)
• Campaign grouping & daily send limits
• Link-click + open tracking
• HTML & plain-text templates

Architecture

packages/
├─ email-service/      # crons, workers, DB migrations
├─ graphql-server/     # API consumed by web-app
├─ web-app/            # Next.js front-end
└─ tracking-service/   # Express endpoints for opens/clicks

PostgreSQL, pnpm monorepo.

Setup

git clone https://github.com/steven4354/sendstack.git
cd sendstack
pnpm install
cp .env.example .env  # fill SMTP keys, DB URL, etc.
pnpm --filter email-service setup:db

Lessons learned

Email deliverability is a deep rabbit hole — domain reputation, warmup, SPF/DKIM/DMARC, content filtering, and more. Building the sending part is straightforward; getting emails into inboxes consistently is the real challenge.