Backend Engineer, MTA

About the Role

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 help the team debug delivery issues by customer, domain, mailbox provider, route, IP, message type, and event - Help design systems that make sending behavior safer, more observable, and easier to operate - Translate reputation strategy into backend systems - Partner with Trust & Safety and Core Sending to build controls that protect Resend’s sending network from abuse - Participate in incident response for sending, provider, and deliverability-sensitive issues - Be on-call for critical services YOU WILL BE A GREAT FIT IF YOU... - Have strong backend engineering experience - Have worked on email, messaging, notifications, communications, infrastructure, or other high-volume delivery systems - Understand queues, workers, retries, idempotency, rate limits, backpressure, and distributed systems - Have experience or strong interest in SMTP, MTAs, DNS, bounces, deferrals, DNS, IP pools, and mailbox-provider behavior - Care about reliability, observability, operational excel

Key Responsibilities

• 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 help the team debug delivery issues by customer, domain, mailbox provider, route, IP, message type, and event

Requirements & Qualifications

• Strong problem solving foundations, knowledge of modern engineering practices, and interest in technology systems.

Perks & Benefits

• Official mentor support
• verified hiring timeline
• and career progression.