Principal Software Engineer, Core Mail Backend

Yahoo Holdings Inc.; Mountain View (CA); Hybrid; USD 143,000 - 300,000; Full time

Job summary

Join a forward-thinking company that operates one of the highest scaling email platforms globally. This role offers you the chance to work on large-scale distributed systems, implementing features that impact millions of users. Collaborate with talented engineers, tackle challenging problems, and continuously innovate within a supportive team environment. With a focus on backend REST APIs and a modern tech stack, you'll play a crucial role in shaping the future of email services. If you are passionate about high-quality code and enjoy the entire product lifecycle, this opportunity is perfect for you.

Benefits

Healthcare

401k

Education Stipends

Flexible Work Options

Qualifications

• 8+ years of experience in backend systems development and leadership.
• Proficiency in Java or C++, with a solid grasp of CS fundamentals.

Responsibilities

• Design and implement features for large-scale distributed systems.
• Lead project teams and collaborate on complex engineering challenges.

Skills

Java

C++

Data Structures

Algorithms

Networking

Object-Oriented Programming

Asynchronous Programming

Multi-threading

Education

BS in Computer Science

MS in Computer Science

PhD in Computer Science

Tools

Kubernetes

CI/CD

GCP

AWS

Job description

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.

About Core Mail

We build, enhance, and maintain one of the highest scaling email platforms on the planet. We are the first component in the mail back end, a middle tier, that contains the APIs and business logic through which virtually all mail operations flow. We implement REST APIs for our world-class mail clients (mobile, web, Yahoo, AOL, etc), standards-based protocols (IMAP, POP, etc) for generic mail clients, and industry leading back-end mail synchronization. We own the data platform in metadata, storage, and indexing. And we build even more supporting systems that are part of or support our array of serving and data components. We share about 20 components implemented in 4M lines of code.

We directly impact approximately 220 Million users every month, serving billions of requests a day across servers & cloud solutions worldwide, and are critical to Yahoo's success. Our logged-in experience offers even greater value to the rest of Yahoo for serving highly customized experiences. We achieve high scale on each server using async technologies developed in house as well as from open source and cloud technologies. We handle hundreds of thousands of connections on a single server or instance to ensure a cost-effective footprint. This role offers a unique opportunity to work on challenging problems at a rare scale, innovate to meet future needs, and continually modernize while sustaining an essential service to users' daily lives.

This is a business critical & central platform to serve all Mail users at Yahoo's core user base & revenue. Join our team to impact user data at high scale, work on the next gen tech stack, and support innovative product experiences to grow users.

A Lot About You

We seek intelligent individuals with strong CS fundamentals, collaborative spirit, quick learners, and a passion for high-quality code. Successful engineers own and drive tasks, consider scenarios and edge cases, learn from leadership, and understand the broader impact. If you enjoy the entire product lifecycle—designing, coding, testing, reviewing, launching, troubleshooting—this is the right place. You will gain hands-on experience with projects that significantly impact Yahoo's success.

Your Day

1. Design, implement, test, and debug our evolving tech stack to support large-scale distributed systems.
2. Develop features supporting mail client functionalities on a large distributed system; refine as needed.
3. Lead project teams, define implementation roadmaps, and execute within business constraints.
4. Implement complex, large-scale work personally.
5. Collaborate with leads and architects on challenging problems.
6. Participate in code reviews and our committer process.
7. Engage in agile development with weekly sprints, planning, and retrospectives.
8. Continuously learn through various sources including on-the-job experience, code reviews, team sessions, and online learning.
9. Proactively identify, solve, and complete problems.
10. Promote and incorporate ideas within the team, seeking buy-in from leads and managers.
11. Contribute to team best practices and culture.

You Must Have

• BS, MS, or PhD in Computer Science or related field with strong academic achievement.
• Proficiency in high-level languages (preferably Java or C++).
• Solid understanding of CS fundamentals, data structures, algorithms, OS, and networking.
• 8+ years of professional experience.
• Experience with software engineering processes and tools for coding, testing, and debugging.
• Significant backend systems development experience.
• Experience with object-oriented programming, large-scale architecture, networking, UNIX/Linux environments.
• Proven leadership on complex projects, including design, task breakdown, and team leadership or solo efforts.
• Excellent communication skills and team collaboration.
• Enjoyment in helping others and maintaining professionalism under stress.

Ideal Candidate

• Experience with large-scale distributed systems (requests, users, compute, data).
• Knowledge of public cloud infrastructure (GCP, AWS).
• Experience with web-scale user bases, traffic, and data.
• Focus on backend REST APIs and business logic.
• Experience with asynchronous programming, multi-threading, containerization (Kubernetes), CI/CD, SSL, and authorization tokens.

Additional responsibilities include adhering to Yahoo policies, exercising sound judgment, working effectively and inclusively, and safeguarding business operations and brand integrity.

Yahoo offers flexible hybrid work options, with occasional in-person requirements. We are an equal opportunity employer committed to diversity and inclusion. For accessibility assistance, please contact us through the provided channels.

The salary range for this role is $143,625.00 - $299,375.00 per year, depending on location, skills, and experience. Benefits include healthcare, 401k, education stipends, and more.

If you currently work at Yahoo, please apply through our internal career site.