Senior IT Systems Engineer

Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find and fix and verify exploitable attack vectors before criminals exploit them. Our flagship product, the NodeZeroTM platform, delivers production-safe autonomous pentests and other key assess...

We are a fusion of former U.S. Special Operations cyber operators, startup engineers, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools, false positives resulting in alert fatigue, blind spots, "checkbox” security culture, c...

We are seeking a security-minded IT Systems Engineer with a genuine passion for networking — someone equally comfortable hardening identity and email infrastructure as they are managing routing and firewall policy. This role is roughly 60% security, identity, and email systems and 40% network engineering.

You will own the controls that protect how our distributed workforce authenticates, communicates, and connects, while keeping the underlying network reliable and well-documented. This role partners closely with Security and the Help Desk team to resolve escalated issues and to keep network, identity, and email infrastructure aligned with company security standards.
This role will be responsible for.....
Administer and secure Okta (or equivalent IdP/SSO), managing authentication policies, access provisioning, and integration with downstream applications
Architecting, Administering and secure the company email/collaboration platform, including mail flow rules, spam/phishing filtering, DKIM/DMARC/SPF configuration, and data loss prevention policies
Own operations, monitoring, and incident response for network, email and identity security controls including firewall policy, and threat detection
Triage incidents and remediate or escalate per incident response procedures
Collaborate across teams (Security and Help Desk) to resolve escalated connectivity issues, support onboarding/offboarding, and ensure infrastructure remains aligned with security standards.
Evaluate and recommend improvements to identity architecture, email security posture, and related tooling
Administer and maintain network infrastructure: switches, routers, firewalls, and wireless access points while also supporting a distributed workforce, including capacity planning and performance monitoring
Design and implement network changes (VLANs, routing, firewall rule changes) with minimal disruption to business operations
Maintain accurate documentation of network topology, configurations, and email/identity security architecture
Manage vendor relationships and support contracts for network, firewall, identity, and email security tooling
Demonstrate a commitment to integrity, process improvement, and customer satisfaction
Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee. Duties, responsibilities, and activities may change at any time with or without notice. 
In any materials you submit, you may redact or remove age-identifying information such as age, date of birth, or dates of school attendance or graduation. You will not be penalized for redacting or removing this information.

Must have hands-on experience administering an identity/SSO platform (e.g., Okta) in a production environment, including access policies and app integrations
Must have experience configuring and maintaining email security controls, including SPF, DKIM, DMARC, and anti-phishing/anti-spam tooling
Must have experience administering a cloud email/collaboration platform (Google Workspace or Microsoft 365, or similar)
Must have hands-on experience administering enterprise network infrastructure (switches, routers, firewalls, VPN) in a production environment
Must have working knowledge of network security principles, including segmentation, firewall policy management, and VPN architecture
Must have experience troubleshooting complex network, identity, and email connectivity issues with minimal escalation
Must have experience documenting configurations, architecture diagrams, and operational runbooks
Must be able to scope and manage moderately complex projects end-to-end with little to no direction
Must have experience supporting a distributed or remote-first workforce
3–5 years of experience in systems administration, identity/security engineering, or network administration
Experience supporting a distributed or remote-first workforce
Identity/SSO platform (e.g., Okta, or similar)
Email security gateway / anti-phishing tooling (e.g., Proofpoint, Mimecast, or similar)
Email/collaboration platform (Google Workspace or Microsoft 365, or similar)
Enterprise firewalls (e.g., Palo Alto, Fortinet, or similar)
Routing and switching (e.g., Cisco, Meraki, or similar)
Network monitoring tools
Relevant certifications such as Security+, CCNA, CCNP, or Okta certifications
Experience with SASE/SSE platforms or Zero Trust network architecture
Experience automating identity, network, or email security tasks via scripting (Python, PowerShell, or similar)
Experience in high-growth SaaS or cybersecurity companies
We are a fully remote company, and this job may require up to 15% of travel to be successful.