Backend Engineer, MTA

Role overview Build and operate the email transport backbone for a developer-focused email platform serving millions of users. The work centers on SMTP delivery, message transfer agent systems, and the infrastructure that keeps sending fast, reliable, and reputation-safe at high scale.

Responsibilities - Build and run email transport systems, including SMTP and MTA components - Design routing, retry, and backoff strategies along with delivery controls - Implement throttling at domain, provider, customer, and IP levels - Develop infrastructure for shared IP pools, dedicated IPs, warmup execution, and reputation-aware routing - Improve classification of bounces, deferrals, transient failures, and hard failures - Create debugging and observability tools that slice delivery data across customer, domain, mailbox provider, route, IP, message type, and event dimensions - Partner with trust, safety, and core sending teams to build abuse protections for the network - Participate in incident response and on-call rotations for critical sending services

Requirements - Strong backend engineering experience on production systems - Background in email, messaging, notifications, communications, or other high-volume delivery infrastructure - Solid grasp of queues, workers, retries, idempotency, rate limits, backpressure, and distributed systems - Hands-on familiarity with SMTP, MTAs, DNS, bounces, deferrals, IP pools, and mailbox-provider behavior - Care for reliability, observability, operational excellence, and limiting blast radius - Comfort with ownership, low-ego collaboration, and a taste for simple system designs

Nice to have - Experience operating high-workload applications - Familiarity with email sending best practices, or a willingness to learn the domain quickly - Proficiency in TypeScript and Go

Benefits and work setup - Fully remote position based in Americas or European time zones - Occasional travel expected for team off-sites, conferences, and meetups - Flexible working schedules - Compensation range of $150,000 to $170,000 USD, commensurate with experience