Principal Network Engineer

Principal Network Engineer About Mimecast

The work people build is worth protecting, and it’s harder to protect than it used to be. AI agents now move at machine speed with human-level access, and a small slip-up can become a very public one. We disrupt cybercriminal activity before that happens. We think fast, go big, and always demand more of ourselves. We work hard, deliver, and repeat.

We grow with real determination and put success well within reach. We push each other to be better and expect to be pushed back, in a community built on respect, where everyone is counted. Work Protected.

Mimecast’s Infrastructure & Operations/IT team is looking for a Principal Network Engineer to own the day-to-day operation, troubleshooting, and continuous improvement of our global corporate network. This role is based in Lexington, MA on a hybrid schedule, with a minimum of two days per week in the office, and reports to the Senior Director, IT Infrastructure. You’ll work hands-on across Cisco, Juniper, and Aruba platforms, partnering closely with IT, Security, and Workspace teams to resolve complex issues, drive strategic upgrades, and use automation to raise operational efficiency worldwide.

You’ll help deliver the reliable, secure, high-performance connectivity that keeps every Mimecaster — wherever they work — seamlessly connected.

• Own the design, build, and maintenance of network infrastructure across Mimecast’s global office locations — including edge routing, enterprise switching, wireless, and out-of-band management — to support a hybrid workforce.

• Monitor, troubleshoot, and resolve complex issues across LAN, WAN, SD-WAN, SASE, and wireless services, ensuring optimal performance and minimal downtime for on-site and remote users.

• Partner with Security to implement and maintain network security policies, access controls, and segmentation strategies that protect corporate assets and user data.

• Partner with Workspace and IT teams to ensure network infrastructure seamlessly supports collaboration platforms, productivity tools, and hybrid work technologies.

• Own comprehensive network documentation, including topology diagrams, configuration standards, runbooks, and change management procedures.

• Lead network upgrade projects and technology refresh initiatives, evaluating new solutions and driving strategic improvements to performance and scalability.

• Leverage automation and scripting to streamline network operations, reduce manual effort, and improve configuration consistency across multi-vendor environments.

• Engage with business stakeholders and end users to understand evolving needs and continuously enhance the digital user experience.

• Demonstrated mastery of enterprise network engineering, with a track record independently designing, implementing, and supporting large-scale, multi-site network infrastructure with minimal oversight.

• Extensive hands‑on expertise with Juniper platforms — including Mist, EX switches, and SRX firewalls — spanning configuration, troubleshooting, and optimization.

• Strong proficiency with Cisco Meraki solutions for cloud‑managed switching, wireless, and security appliances.

• Proven ability deploying and managing Aruba wireless infrastructure across enterprise environments with multiple sites and diverse user populations.

• Working knowledge of Opengear or similar out‑of‑band management platforms for remote device access and network recovery.

• Experience with SASE and ZTNA solutions supporting secure hybrid cloud and remote workforce connectivity.

• Comprehensive enterprise wireless planning expertise, including RF site surveys, heat mapping, interference analysis, capacity optimization, and evolving Wi‑Fi 6/6E/7 standards.

• Solid command of core…