Machine Learning Engineer

or a related quantitative field, with 2+ years hands-on experience in building and running ML systems.

Production-level ML expertise:

You’ve shipped models that handle real-world scale and complexity.

Hands-on experience with LLMs

in agentic environments.

Proficiency in Python, with a solid understanding of backend and server fundamentals.

Impact at scale

: Your work will protect millions of users globally.

Cutting-edge tech

: Tackle challenges like agentic AI, real-time threat detection, and privacy-preserving ML.

Collaborative culture

: Work with a global team of experts in security, ML, and systems engineering.

The MSA team (Mail Delivery, Spam, and Anti-Abuse) is a multidisciplinary group founded in 2019 to solve complex security challenges across the Proton ecosystem.

We build sophisticated systems from scratch that combine human intelligence and machine learning to make tens of millions of real-time or asynchronous decisions daily.

Mail delivery and spam prevention

Site reliability and resilience

Over the past few years, our custom systems have:

Reduced spam filter misclassifications by