Senior Software Engineer - Email Channel

Details

Customer.io is looking for an experienced software engineer to own the email channel end to end, from infrastructure that delivers billions of messages reliably to product surfaces used to create, send, and analyze campaigns. The role spans backend systems, frontend product experiences, email deliverability, observability, and production operations.

Responsibilities

• Build and evolve frontend experiences for creating, previewing, and analyzing email campaigns, including template editors, sending configuration, and deliverability dashboards.
• Design and scale backend systems for high-volume email sending, including queue management, retry logic, and event processing for bounces, complaints, and deferrals.
• Own deliverability-adjacent systems such as bounce classification, suppression management, IP and domain reputation monitoring, and feedback loop processing.
• Partner with the deliverability team to build automated tooling for reputation scoring, warm-up schedules, and sending throttles.
• Instrument and monitor email channel health, including inbox placement signals, block detection, ESP feedback, and alerting.
• Own projects end to end, including architecture and schema design, testing, deployment, and monitoring.
• Share knowledge and raise engineering standards through short videos, thoughtful writing, and mentorship.
• Use AI agents to make multi-file changes by scoping work, writing prompts, and verifying output.

Requirements

• 7+ years of experience building scalable, distributed systems in Go or similar statically typed languages.
• Experience building product-facing frontend features in React or similar frameworks, with attention to UX quality and polish.
• Comfort working in cloud-native environments such as AWS or GCP.
• Familiarity with relational databases; Customer.io primarily uses MySQL.
• Understanding of database performance tradeoffs.
• Familiarity with high-volume email sending concepts, including bounce handling, feedback loops, and delivery event processing.
• Working knowledge of SPF, DKIM, and DMARC and their impact on deliverability.
• Ability to reason about sender reputation, IP warm-up, and ISP behavior at scale.
• Experience with observability tooling and operating production systems.
• Experience building or consuming APIs that handle high-throughput asynchronous workloads.
• A bias for action and a willingness to own technical decisions.

Compensation And Benefits

• Starting salary of $150,000–$200,000 USD, or equivalent in local currency, depending on experience and subject to market rate adjustment.
• 100% coverage of medical, dental, vision, mental health, and supplemental insurance premiums for employees and their families.
• 16 weeks of paid parental leave.
• Unlimited PTO.
• Remote work and wellness stipends.
• Professional development budget.

Hiring Process

• Application review.
• 30-minute recruiter call.
• 60-minute behavioral interview.
• 60-minute technical interview focused on system design and scaling challenges.
• Take-home assignment.
• 60-minute assignment review call.
• 60-minute project deep dive focused on an end-to-end technical project and balancing planned work against urgent, customer-impacting issues.

Final candidates must complete a background check and employment verifications. Virtual interviews are conducted using Zoom. Customer.io is committed to inclusion, equity, and bias-free hiring practices.