Customer.io
SaaS
SeniorSoftwareEngineer-EmailChannel
Neural analysis suggests this role is
optimal for Senior candidates.
“Senior Software Engineer - Email Channel at Customer.io. Skills: Go, React, Email channel development, Scalable distributed systems, Cloud-native environments, High-volume email sending. Own the email channel end to end — from the infrastructure that delivers billions of messages reliably, to the product surfaces our customers use to build, send, and analyze their campaigns.. Work across the stack, bringing both systems thinking and product craft to one of the most technically rich channels in t”
What You'll Achieve.
Deliver billions of messages reliably; Build product surfaces our customers use to build, send, and analyze their campaigns; Scale backend systems that power high-volume email sending; Own deliverability-adjacent systems; Translate domain expertise into automated tooling; Instrument and monitor the health of the email channel; Raise the bar through short videos, thoughtful writing, and mentorship; Make multi-file changes using AI agents
Industry & Context.
Systems thinking; Product craft; Reasoning about sender reputation, IP warm-up, and ISP behavior at scale; Scoping the work; Writing the prompt; Verifying the output
Background check, Employment verifications
What They're Looking For.
Must Have
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 (AWS, GCP), Familiarity with relational databases (we use MySQL primarily) and an understanding of performance tradeoffs, Familiarity with high-volume email sending concepts: bounce handling, feedback loops, and delivery event processing, Working knowledge of email authentication standards — SPF, DKIM, DMARC — and how they affect deliverability, Comfortable reasoning 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 async workloads, A bias for action over perfection, and pride in owning technical decisions
Nice to Have
Channel depth You understand the email ecosystem: how messages are routed, authenticated, delivered, and measured. You bring that knowledge into both your backend architecture and the product experiences you build on top of it.
What You'll Do.
Own the email channel end to end — from the infrastructure that delivers billions of messages reliably
to the product surfaces our customers use to build
and analyze their campaigns.
Work across the stack
bringing both systems thinking and product craft to one of the most technically rich channels in the industry.
Build and evolve the frontend experiences customers use to create
and analyze email campaigns — template editors
sending configuration
deliverability dashboards
Design and scale the backend systems that power high-volume email sending
including queue management
and event processing (bounces
Own deliverability-adjacent systems: bounce classification
suppression management
IP/domain reputation monitoring
and feedback loop processing
Partner with our deliverability team to translate domain expertise into automated tooling — reputation scoring
Instrument and monitor the health of the email channel: inbox placement signals
Own problems end to end — from architecture and schema design to testing
Share knowledge and raise the bar through short videos
Use AI agents to make multi-file changes by scoping the work
and verifying the output
How You'll Work.
Team & Collaboration
Partner with our deliverability team to translate domain expertise into automated tooling; Share knowledge and raise the bar through short videos, thoughtful writing, and mentorship
Communication Scope
Thoughtful writing; Share knowledge
Process & Methodology
Led complex projects before, Own problems end to end, Balance planned work against urgent, customer-impacting issues
Full Job Description
Hi, I'm Brian, Senior Director of Engineering at Customer.io. We're looking for experienced engineers who want to own the email channel end to end — from the infrastructure that delivers billions of messages reliably, to the product surfaces our customers use to build, send, and analyze their campaigns. You'll work across the stack, bringing both systems thinking and product craft to one of the most technically rich channels in the industry. About Customer.io Over 8,000 companies — from scrappy startups to global brands — use our platform to send billions of emails, push notifications, in-app messages, and SMS every day. Customer.io powers automated communication that people actually want to receive. We help teams send smarter, more relevant messages using real-time behavioral data. Under the hood: Go, React, Ember and AI help us ship fast and scale with confidence. What We Value Ownership You own problems end to end. You move fast, act like an owner, and thrive in ambiguity. You've led complex projects before, whether officially or not, and you're ready to do it again. Engineers with product taste You think like a user, not just an engineer. You care how your systems power real customer value — and how to make them better. A healthy skepticism for "the way things are done" You bring rigor and creativity. Best practices matter — but never more than forward motion. Channel depth You understand the email ecosystem: how messages are routed, authenticated, delivered, and measured. You bring that knowledge into both your backend architecture and the product experiences you build on top of it. What You'll Do Build and evolve the frontend experiences customers use to create, preview, and analyze email campaigns — template editors, sending configuration, deliverability dashboards Design and scale the backend systems that power high-volume email sending, including queue management, retry logic, and event processing (bounces, complaints, deferrals) Own deliverability-adjacent
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