Campaign dashboard summarizing campaign progress, per-contact deliverability status, and connected mailbox quotas.
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Selected project
MailFlow — Outreach & Campaign Manager
A self-hosted outreach and campaign management platform that connects user mailboxes (Gmail/Outlook), queues sends, tracks opens via a first-party pixel, detects bounces and replies, and surfaces campaign and per-contact status in a multi-tenant dashboard.
Access
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Project overview
MailFlow is a self-hosted outreach platform that lets users connect their Gmail or Outlook accounts to send tracked campaigns from their own mailboxes. It queues sends with pacing and per-account rate limits, classifies opens using a first-party pixel, and scans connected inboxes to detect replies and hard bounces.
The challenge
Sending from user mailboxes requires careful token handling, pacing per-account daily caps, reliable correlation between outgoing Message-IDs and inbox events, and a first-party open classifier to filter provider image proxies from human opens.
Build decisions
Keep sending on behalf of users
Use provider APIs (Gmail, Microsoft Graph) with a separate mailbox-consent grant so sends and inbox scans operate under the user's explicit mailbox access without conflating auth sessions.
Queue and pace sends
Use pg-boss to schedule and throttle sends per connected account to respect provider limits and reduce risk of rate-related errors.
First-party open tracking
Serve a tracking pixel from our backend and run a bot/proxy classifier so only likely human opens increment the opened metric.
Delivery shape
Delivered as a pnpm monorepo with separate frontend and backend apps, Prisma migrations for PostgreSQL, Better Auth for identity, pg-boss workers for scheduled sends, mailbox integrations using Gmail and Microsoft Graph, an inbox scanner for replies/bounces, and a manual campaign dashboard with CSV import and template support.