Backend Engineer, MTA

Resend is building the most accessible email platform for developers. As we’ve grown to 4M+ users and continue to onboard thousands of new users every day, the pressure of maintaining a safe place for good senders continues to build. This role is fully remote-based in Americas or European time zones, with some expected travel for team off-sites, conferences, meetups, and more. Read more about how we work, how we hire, and what we value here https://resend.com/handbook. IN THIS ROLE, YOU WILL… - Build and operate Resend’s email transport infrastructure - Work on SMTP delivery, MTA systems, routing, retries, backoff strategies, and delivery controls - Design systems for domain-level, provider-level, customer-level, and IP-level throttling - Build infrastructure for shared IP pools, dedicated IPs, warmup execution, and reputation-aware routing - Improve how Resend classifies bounces, deferrals, transient failures, hard failures, and delivery outcomes - Build tools that h