Objective Build a web-based SaaS platform that helps users create and manage pre-warmed mailboxes with automated domain setup (SPF, DKIM, DMARC) and integrations for cold-email tools like Lemlist, Instantly, and Reply.io. Core Features (MVP Scope) 1. User Dashboard (Frontend) Built with Next.js (React + Tailwind CSS). Secure login / signup via email + password + JWT session. Dashboard sections: Mailboxes: Add, view, or delete mailboxes. Domains: Add or connect custom domains. DNS Setup: Show generated DNS records for SPF, DKIM, DMARC. Warmup Status: Progress bar and daily activity chart. Integrations: Connect Lemlist, Instantly, Reply, etc. Billing: Stripe checkout & subscription status. Support / Docs: Static pages with FAQ. 2. Backend (API Layer) Stack: Node.js (Express) or Python (FastAPI). Database: PostgreSQL (Supabase / RDS). Authentication: JWT-based. Core Endpoints: POST /api/domains – Add or register new domain. GET /api/domains/:id/records – Retrieve SPF/DKIM/DMARC entries. POST /api/mailboxes – Provision mailbox (Google/Microsoft). GET /api/mailboxes/:id/status – Return warmup & health metrics. POST /api/integrations/:provider – Connect outreach tool. GET /api/metrics/:mailboxId – Return inbox rate, bounces, spam, etc. POST /api/payment/webhook – Handle Stripe events. 3. DNS Automation Auto-generate records: SPF → v=spf1 include:_spf.google.com -all DKIM → unique key per mailbox. DMARC → v=DMARC1; p=none; rua=mailto:dmarc@domaindotcom. Use APIs (Cloudflare, Google Cloud DNS, or Route53) for automated record setup. Verify each DNS record before enabling sending. 4. Email Warmup Engine Internal scheduler that sends small batches of emails between “warmup pool” mailboxes. Simulate replies, opens, and clicks to build trust. Store warmup logs and show a simple progress metric. Respect rate limits to avoid blacklisting. 5. Integrations REST/webhook connectors for: Instantly Lemlist Reply.io Ability to push new warmed mailboxes to those platforms via API key or OAuth. 6. Admin Panel (Internal Use) View all users, mailboxes, domains. Suspend or throttle users if bounce rate is high. View API logs, DNS verification results, and warmup queue health. 7. Billing & Subscription Stripe integration (monthly plans). Plans: Starter – 5 mailboxes Growth – 25 mailboxes Agency – 100 mailboxes Automatic mailbox deactivation on payment failure. 8. Infrastructure & Deployment Hosting: AWS (EC2 + RDS) or GCP (Compute + Cloud SQL). CI/CD via GitHub Actions. Monitoring: UptimeRobot or New Relic. Email infrastructure: use Google Workspace API / Microsoft Graph API for provisioning. Technical Requirements Clean, modular code with API documentation (Swagger/OpenAPI). Reusable components, scalable architecture. Deployment instructions (Docker preferred). Security: input validation, rate limiting, and HTTPS everywhere.