Google Sheets → Instantly Automation Setup Required

* I currently use Google Sheets to write emails, filter my contact list, and trigger sending. I want to keep this exact workflow. * I need a multi-domain, multi-inbox cold email setup (like Instantly or similar) for excellent Inbox deliverability. * You must set up the entire backend system, including inboxes, domains, warm-up, and deliverability management. * The automation must connect my Google Sheets to the backend so that sending happens through the configured infrastructure. * I want to keep it simple: I do everything in Google Sheets, and your automation handles the rest flawlessly. * No breakdowns: The automation must run smoothly—no errors or manual intervention needed. * The system should allow me to send up to 300 emails per day. * In summary, I want the deliverability and scalability of Instantly (or similar) with none of their interface—Google Sheets remains my front-end. Proven experience in cold email and automation required.