Senior IT Systems Engineer - M365, Security & Automation

RethinkFirst; Atlanta (GA); On-site; USD 110,000 - 140,000; Full time

Job summary

RethinkFirst in Atlanta, GA seeks a Senior Systems Engineer to administer and harden enterprise IT infrastructure, focusing on Microsoft 365, Entra ID, Intune, Defender, endpoints and network services. This hands-on role requires troubleshooting complex issues, automating repeatable tasks, and coordinating with IT, Security and external providers to improve reliability and security.

The successful candidate will contribute to incident response, implement approved changes, develop PowerShell

Qualifications

• Availability to work in person at the Atlanta, GA office to support employees, office technology, and infrastructure needs.
• 5+ years of progressive experience in systems administration, infrastructure engineering, or a related role, including independent resolution of complex production issues.
• Strong hands-on administration experience with Microsoft 365, Entra ID, Intune, Microsoft Defender, and enterprise endpoints; working knowledge of identity and endpoint security practices.
• Practical experience troubleshooting TCP/IP, DNS, DHCP, routing, switching, firewalls, and VPN connectivity, and interpreting system logs and monitoring data.
• Proficiency with PowerShell and experience building maintainable automation; familiarity with Jira ITSM and incident, problem, and change management practices.
• Ability to prioritize technical work, document clearly, communicate with technical and nontechnical colleagues, and collaborate effectively during incidents and infrastructure changes.
• Bachelor’s degree in information technology, computer science, or a related field, or equivalent practical experience.

Responsibilities

• Administer Microsoft 365 services, including Exchange Online, Teams, SharePoint Online, and OneDrive; resolve complex availability, configuration, access, and service integration issues.
• Maintain Entra ID identities, groups, enterprise applications, single sign‑on, multifactor authentication, and Conditional Access in accordance with approved security and access standards.
• Administer Intune device enrollment, configuration profiles, application deployment, compliance policies, and endpoint updates; troubleshoot deployment failures and maintain secure endpoint configurations.
• Configure and maintain Microsoft Defender protections in partnership with Security; investigate endpoint alerts and carry out approved containment, remediation, and vulnerability‑reduction actions.
• Provide general IT troubleshooting for Wi‑Fi, wired networks, internet access, and VPN connectivity, including DNS, DHCP, routing, switching, and firewalls; implement approved changes and coordinate complex resolutions with providers.
• Serve as a senior technical escalation point for issues spanning identity, endpoints, collaboration services, and networks. Use logs, diagnostic tools, and structured testing to isolate root causes and implement durable fixes.
• Use Jira ITSM to document and progress incidents, service requests, problems, and changes; maintain accurate technical notes, impact assessments, resolution details, and knowledge articles.
• Set up, configure, and troubleshoot office video conferencing equipment and meeting room systems, including cameras, microphones, displays, and Microsoft Teams connectivity.
• Provision and configure employee IT equipment, user access, and network connectivity for onboarding and office changes; validate that devices and services are ready for use.
• Improve monitoring and alerting, investigate service health and performance trends, and work with NOC teams or providers to address alerts and recurring issues in a 24x7 operating environment.
• Participate in incident response under the designated incident commander. Perform technical investigation and recovery, provide timely findings, and contribute to post‑incident reviews and corrective actions.
• Develop, test, and maintain PowerShell scripts and other automation for administration, provisioning, reporting, and remediation; apply version control, error handling, and secure credential practices.
• Plan and execute approved upgrades, patches, migrations, and configuration changes with testing, rollback procedures, and post‑change validation. Support backup verification and recovery testing for assigned systems.
• Maintain system documentation, configuration records, network diagrams, operating procedures, and recovery runbooks. Share technical knowledge and provide peer guidance to improve support effectiveness.
• Support HITRUST and SOC 2 activities by collecting evidence, maintaining accurate records, assisting with access reviews, and completing assigned control remediation in partnership with Security and Compliance.
• Collaborate with service desk staff, engineering teams, business stakeholders, and vendors to resolve dependencies, communicate technical risks, and deliver reliable infrastructure improvements.

Skills

PowerShell scripting

Automation

Incident response

Documentation

Communication

Education

Bachelor's degree in Information Technology / Computer Science

Tools

Microsoft 365

Entra ID

Intune

Microsoft Defender

VPN

Job description

RethinkFirst in Atlanta, GA seeks a Senior Systems Engineer to administer and harden enterprise IT infrastructure, focusing on Microsoft 365, Entra ID, Intune, Defender, endpoints and network services. This hands-on role requires troubleshooting complex issues, automating repeatable tasks, and coordinating with IT, Security and external providers to improve reliability and security.

The successful candidate will contribute to incident response, implement approved changes, develop PowerShell