I need a scalable, dynamic, and inbox-friendly email system that can send unique emails using Gmail API and multiple other domains. This system should use a Redis Queue Worker setup with 40 initial workers, easily upgradeable to 100+ workers in the future. All workers must operate using single centralized credentials without separate user login, maintaining centralized configuration, monitoring, and rate-limiting. Core Features: 1. Dynamic & Unique Emails - Each email is unique: Subject, Body, Name, Phone, Images, Buttons, GIFs. - Modern responsive HTML templates with inline CSS. - Inline images (base64 or CID) and optional attachments. - Personalized merge fields (Name, Phone, Location, Preferences). - Optional dynamic features: Buttons, Countdown Timers, Embedded GIFs/Videos. - Multipart emails (HTML + Plain Text) to ensure inbox delivery. 2. Multi-Domain Support - Gmail, Yahoo, Outlook, and custom domains using SMTP/IMAP or API. - Dynamic credential configuration per domain. - Rate-limiting and queue management per domain. - DKIM/SPF/DMARC compliance for each domain. 3. Queue & Workers - Redis queue with 40 concurrent workers (upgradeable to 100+). - Centralized rate-limiting and retry mechanism for failed emails. - Centralized monitoring dashboard showing worker status, emails sent/failed, rate-limiting stats. 4. Single Credential / No User Login - All workers operate using a single OAuth token or centralized credential. - No separate user login or session management required. - Centralized configuration for easier maintenance. 5. Inbox-Friendly & Spam-Proof - Balanced text and images to avoid spam triggers. - Avoid spammy keywords and URL shorteners. - Fully compliant with DKIM, SPF, and DMARC. Required Skills: - Python / Node.js - Gmail API & SMTP/IMAP integration - Redis / Celery / Queue Worker management - HTML Email Design & Responsive Templates - OAuth 2.0 Authentication - Logging, Monitoring & Dashboard Budget: $180–$200 USD (negotiable depending on complexity) Timeline: 1–2 weeks (development + testing) Additional Instructions: - Demo Version: Provide a small demo before full implementation (5–10 sample emails). - Full Setup: After approval, implement full Redis Queue system with 40+ workers and all dynamic features. - Scalability: System should support scaling up to 100+ concurrent workers in the future without major redesign.