Principal AI/ML Engineer, Yahoo Mail

Yahoo Mail is the ultimate consumer inbox with hundreds of millions of users. It’s the best way to access your email and stay organized from a computer, phone or tablet. With its beautiful design and lightning fast speed, Yahoo Mail makes reading, organizing, and sending emails easier than ever.

A Little About Us

Yahoo Mail serves over 220M users globally and operates at massive scale—billions of inbound connections and trillions of messages. Our vision is to be the best consumer inbox that helps users run the business of their lives.

The Mail Intelligence AI/ML Platform powers intelligent capabilities across Yahoo Mail and the broader Yahoo ecosystem. We build systems that extract meaning from unstructured content, understand user context and intent, and deeply personalize user journeys at scale.

We are evolving beyond traditional ML into agentic, assistive, and proactive intelligence—systems that don’t just classify or recommend, but reason, act, orchestrate workflows, and assist users autonomously and responsibly.

A Lot About You

As a Principal AI/ML Engineer (IC5), you will architect and deliver large-scale intelligent systems that power:

• Agentic inbox experiences (automated task completion, workflow orchestration)

• Assistive intelligence (context-aware drafting, summarization, prioritization)

• Hyper-personalized recommendations and insights

• LLM-powered reasoning and multi-step action frameworks

• Real-time and batch inference systems at massive scale

You will operate across squads, influence architecture, and translate ambiguous business problems into scalable technical strategy—consistent with IC5 expectations in scope, delivery, and architecture.

Agentic & Assistive AI Systems

• Design and implement agentic frameworks that can:

  • Understand user intent

  • Reason over inbox context

  • Take safe, explainable actions

  • Orchestrate multi-step workflows

• Build assistive AI features such as smart compose, summarization, task extraction, auto-categorization, and contextual recommendations.

• Integrate LLMs with structured ML systems using hybrid retrieval + reasoning architectures.

Personalization at Scale

• Architect large-scale personalization systems using:

  • User segmentation

  • Behavioral modeling

  • Contextual bandits / ranking systems

  • Deep learning and LLM-enhanced personalization

• Build and optimize models for information extraction, clustering, classification, and recommendation.

Inference & Infrastructure Ownership

• Take end-to-end ownership of cost-effective and scalable inference systems for:

  • Deep learning models

  • Large Language Models

  • Real-time personalization pipelines

• Drive architectural decisions balancing latency, cost, quality, and reliability

• Improve ML data infrastructure for petabyte-scale training and inference workloads

Technical Leadership

• Translate ambiguous business requirements into clear technical strategy

• Influence architecture across multiple squads

• Simplify complex systems and mitigate long-term technical risk

• Mentor engineers and raise the engineering bar

• Lead investigations and root-cause production issues across ML pipelines

Qualifications

• Bachelor's degree or Master's degree in Computer Science or related discipline

• 8+ years of relevant industry experience

• Strong experience in:

  • ML/Deep Learning frameworks (TensorFlow, PyTorch, Spark MLlib)

  • NLP and/or LLM systems

  • Large-scale ML inference infrastructure  (vLLM, TensorRT-LLM, Triton, ONNX runtime)

• Strong distributed systems fundamentals (algorithms, data structures, databases)

• Proficiency in Java, Python, or C++

• Experience deploying production-grade ML in public cloud environments (GCP preferred)

• Familiar with AI tools like Cursor, Copilot, and Claude

Preferred Qualifications

• Experience with agent frameworks (ReAct, tool-augmented LLMs, retrieval-augmented generation)

• Experience building AI safety, guardrails, evaluation, and red-teaming systems

• Experience with Hadoop ecosystem (Spark, Hive, Kafka, HBase)

• Experience running large-scale experimentation platforms (A/B testing, model evaluation)

The material job duties and responsibilities of this role include those listed above as well as adhering to Yahoo policies; exercising sound judgment; working effectively, safely and inclusively with others; exhibiting trustworthiness and meeting expectations; and safeguarding business operations and brand integrity.

At Yahoo, we offer flexible hybrid work options that our employees love! While most roles don’t require regular office attendance, you may occasionally be asked to attend in-person events or team sessions. You’ll always get notice to make arrangements. Your recruiter will let you know if a specific job requires regular attendance at a Yahoo office or facility. If you have any questions about how this applies to the role, just ask the recruiter!

Yahoo is proud to be an equal opportunity workplace. All qualified applicants will receive consideration for employment without regard to, and will not be discriminated against based on age, race, gender, color, religion, national origin, sexual orientation, gender identity, veteran status, disability or any other protected category. Yahoo will consider for employment qualified applicants with criminal histories in a manner consistent with applicable law. Yahoo is dedicated to providing an accessible environment for all candidates during the application process and for employees during their employment. If you need accessibility assistance and/or a reasonable accommodation due to a disability, please submit a request via the Accommodation Request Form (www.yahooinc.com/careers/contact-us.html) or call +1.866.772.3182. Requests and calls received for non-disability related issues, such as following up on an application, will not receive a response.

We believe that a diverse and inclusive workplace strengthens Yahoo and deepens our relationships. When you support everyone to be their best selves, they spark discovery, innovation and creativity. Among other efforts, our 11 employee resource groups (ERGs) enhance a culture of belonging with programs, events and fellowship that help educate, support and create a workplace where all feel welcome.

The compensation for this position ranges from $143,625.00 - $299,375.00/yr and will vary depending on factors such as your location, skills and experience.The compensation package may also include incentive compensation opportunities in the form of discretionary annual bonus or commissions. Our comprehensive benefits include healthcare, a great 401k, backup childcare, education stipends and much (much) more.

Currently work for Yahoo? Please apply on our internal career site.