Senior ML Engineer - Email Security (Remote)

About the role

CloudLinux develops Imunify Email, an email security product protecting hosting servers against spam, phishing and other email threats. It is looking for a Senior Machine Learning Engineer to work alongside the engineer responsible for the existing spam-filtering pipeline and the new ML model, driving its development, improvement and production rollout. The role is fully remote.

Key responsibilities

• Train, evaluate and release spam-detection models: build the corpus, set thresholds, review precision/recall reports and decide whether to ship or retrain.
• Build the production side of the new engine in Go: inference service, mail-filter integration, tokenizer and streaming message parser.
• Fix detection quality end to end, weighing false positives against messages caught.
• Keep the corpus tooling and training infrastructure running.
• Review and approve classifier, rule and model changes so releases do not wait on one person.
• Answer partner engineers' questions about message scores.
• Write specs, handbooks and post-mortems to share knowledge.

Required profile

• 5+ years shipping detection or classification systems where false positives matter (anti-spam, anti-phishing, anti-malware, fraud, abuse).
• At least one ML classifier taken to production, including corpus construction, threshold selection and error analysis.
• Hands-on transformer training in PyTorch, with daily use of AI coding agents and tools.
• English at B2 level or higher, with strong written communication for documentation, specs and code reviews.

Required skills

• PyTorch, transformers, ONNX export, Linux, shell and Python.
• Strong plus: Go or Rust for systems code; rspamd or SpamAssassin internals; multi-million sample corpora and labelling pipelines; small models for constrained hardware; LLM-based labelers; hosting panels such as cPanel, Plesk and DirectAdmin.

What we offer

• Fully remote work with flexible hours, paid 24 days of vacation, 10 national holidays and unlimited sick leave.
• Private medical insurance, co-working and gym reimbursement, and a budget for education.
• A chance to win a reward for the most innovative idea the company can patent.