Software Engineer II - Inline Mailflow

Abnormal AI is looking for a Software Engineer to join the newly formed Inline Mailflow team, which is building next-generation SMTP relay infrastructure for outbound email security. The role involves designing and implementing core components of the SMTP relay harness and collaborating with various teams to ensure reliable configurations and high service availability.

Responsibilities:

• Design and implement core components of the SMTP relay harness, including Mail Transfer Agent (MTA) infrastructure, scalability, IP management, encryption, and DMARC support, working from conception through production operation
• Co-build the production relay alongside existing infra engineers, ramping toward full ownership of defined services as the product matures through Q3 and into EA
• Collaborate with PMs and Solutions Architects to translate customer requirements into reliable, opinionated relay configurations that support inbound and outbound use cases
• Own and operate tier-0 mail flow services that handle high volumes of enterprise email at production SLA, participating in on-call rotations and driving continuous reliability improvements
• Contribute to technical design discussions on how the relay integrates with existing inline products (outbound DLP, behavioral outbound, misdirected email), helping define the architecture of the broader Mail Flow platform
• Raise the bar of engineering excellence by contributing to knowledge sharing, runbooks, and professional development within the team

Requirements:

• BS degree in Computer Science, Applied Sciences, Information Systems, or a related engineering field
• 3+ years of backend software development experience with distributed systems, designing and building production services
• Hands-on experience with our stack: Go and/or Python
• Experience building features and components from scratch and owning them in production, balancing feature development with operational work
• Comfortable with ambiguity and 0-to-1 projects where you help shape requirements alongside product and engineering stakeholders
• Experience working with distributed teams; proficient in asynchronous and written communication
• Solid understanding of email protocols and infrastructure (SMTP, MTA architecture, DNS, SPF/DKIM/DMARC)
• Experience with our extended stack: AWS, Kubernetes, Django, Spark, Prometheus
• Familiarity with email security products or Secure Email Gateways (SEGs) such as Proofpoint, Mimecast, or Microsoft Defender
• Experience with email deliverability concepts: IP reputation, bulk sending infrastructure, bounce handling, or feedback loops
• Familiarity with containerization using Docker or similar technologies