Backend Developer - Anti-Abuse & Email Systems

Sinch is pioneering the way the world communicates. More than 150,000 businesses — including Google, Uber, Paypal, Visa, Tinder, and many others — rely on Sinch’s Customer Communications Cloud to power engaging customer experiences through mobile messaging, voice, and email.

Whether you need to verify users or craft omnichannel campaigns, Sinch makes it easy. Our AI-infused Super Network, APIs, and applications ensure you can connect with your customers reliably and securely, at every step of their journey.

At Sinch we “Dream Big”, “Win Together”, “Keep it simple”, and “Make it Happen”. These values are our foundation!

We’re looking for a (Senior) Backend Developer to join our Core Engineering team, with a focus on email reputation, deliverability, and anti-abuse systems. You’ll play a key role in ensuring our platform stays a trusted space for legitimate communication by detecting, preventing, and mitigating abuse or fraudulent behavior. 

In this role, you’ll work closely with our deliverability and compliance teams to design, build, and maintain systems that protect our platform and our users’ reputation. You'll address critical issues related to sender reputation, regulatory compliance, and abuse prevention, while contributing to our CORE platform (sending pipeline and APIs).

You’ll work on high-performance backend services in Go and PHP and contribute to systems that operate at massive scale and with high availability requirements. This is a high-impact role where your decisions will directly influence platform integrity and customer trust.

We believe you’re experienced, autonomous, and collaborative, comfortable navigating complex architectures to drive forward improvements with distributed teams across multiple time zones. 

What You'll Do 

Reputation & Compliance 

• Design, build, and maintain systems to monitor, score, and react to user behavior and sending patterns.
• Partner with deliverability and compliance teams to translate business needs and develop mechanisms for abuse detection and mitigation.
• Integrate with existing infrastructure and services, ensuring resilience, scalability, and performance.  
• Analyze production traffic, identify anomalies, and implement safeguards to protect platform reputation.  
• Shape architectural and technical decisions in a live, distributed, high-throughput environment.  
• Proactively contribute to discussions around data quality, scoring models, email authentication (SPF, DKIM, DMARC), and IP/domain reputation.  
• Respond to and learn from incidents related to abuse or reputation loss.

CORE Development 

• Contribute to Mailjet's sending pipeline development.
• Maintain and evolve our public APIs.

• Proven practical backend development experience with Go.
• Strong exposure to PHP, with the ability to apply it in practical applications.
• Solid understanding of large-scale, high-availability systems and distributed architectures.  
• Strong experience with email infrastructure, anti-abuse, or reputation systems.  
• Experience analyzing traffic patterns and working with large volumes of behavioral or event data.  
• Proficiency with relational/NoSQL databases.
• Excellent communicator with experience working in remote, cross-functional teams.  
• Strong sense of ownership, pragmatism, and security awareness. 
• Comfortable working autonomously and making decisions in a complex environment.

Preferred Qualifications 

• Experience in email deliverability, anti-spam techniques, and authentication protocols (SPF, DKIM, DMARC).  
• Knowledge of SMTP protocol and feedback loop integration.  
• Familiarity with compliance frameworks or regulatory environments (GDPR, CAN-SPAM, etc.).  
• Experience with data pipelines or streaming tools (e.g., Kafka, Pub/Sub).  
• Familiarity with observability tools (e.g., Prometheus, Grafana, ELK).  
• Background in SaaS or large-scale messaging platforms.  

Our corporate language is English, please submit your application in English.

At Sinch, we value learning, embrace change, and offer opportunities for personal and professional growth. Unfortunately, we are not supporting relocation outside the EU at this time. Applicants must:

• Hold French or EU/EEA citizenship.
• Have a valid French work permit.

We are committed to ensuring a recruitment process that is fair, objective, consistent, and inclusive. Our approach includes structured, competency-based interviews designed to evaluate your skills, experience, and qualifications relevant to the role. At times, we may include a data-driven assessment to enhance our hiring success and identify candidates likely to excel.

We believe in a two-way process and encourage you to ask questions throughout the journey.  If this role isn't what you're looking for, please explore the other opportunities listed on our career page: . No matter who you are, we hope you find an exciting path forward - hopefully with us!