Backend Engineer, MTA

Description: Build and operate Resend’s email transport infrastructure. Work on SMTP delivery, MTA systems, routing, retries, backoff strategies, and delivery controls. Design systems for throttling at various levels (domain, provider, customer, IP). Improve classification of bounces, deferrals, and delivery outcomes. Build debugging tools for delivery issues. Design safer and more observable sending behavior systems. Partner with Trust & Safety to protect the sending network. Participate in incident response and be on-call for critical services. Requirements: Strong backend engineering experience. Experience with email, messaging, or high-volume delivery systems. Understanding of queues, workers, retries, and distributed systems. Experience or interest in SMTP, MTAs, DNS, and mailbox-provider behavior. Commitment to reliability, observability, and operational excellence. Low ego, high ownership, and preference for simple systems. Experience with high workload applications is a plus. Knowledge of email best practices or willingness to learn. Proficiency in Typescript and Golang is preferred. Benefits: Autonomy to "just ship it" in a flexible remote work environment. Modern tech stack (Typescript, AWS, Go, Postgres, Datadog). Honest and low-ego team culture. Ownership of problems and solutions. Competitive salary range of $150,000 - $170,000 USD, based on experience.