Sr. Systems Administrator - Office 365 / Exchange

Senior System Administrator – Messaging & Collaboration Systems

Job Summary

This senior-level technical position requires deep, hands-on expertise with Microsoft Exchange (both on-premises and Exchange Online), Microsoft 365 tenant administration, and enterprise messaging security platforms. The ideal candidate will have extensive experience designing, administering, and supporting hybrid Exchange environments, Proofpoint, eDiscovery, PRA, and compliance frameworks.

This role serves as a technical leader within the SysAdmin team and is responsible for ensuring secure, reliable, high-performance communication systems across the organization. The environment spans multiple sites, datacenters, and a hybrid cloud infrastructure.

This position requires passing a CLETS background check and eligibility to work in the United States.

Duties and Responsibilities

Messaging & Collaboration Systems Administration

• Lead administration of Microsoft Exchange on-premises including DAG configuration, mailbox databases, connectors, transport rules, and hybrid mail flow.
• Oversee Exchange Online and Microsoft 365 messaging services, ensuring performance and compliance.
• Manage hybrid environments including Entra Connect, identity sync, and coexistence strategies.
• Maintain and optimize Proofpoint (email security, DLP, TAP, encryption, routing).
• Support Teams/Outlook integration, shared mailboxes, and mail routing.

Security, Compliance, and Governance

• Manage eDiscovery, PRA, retention, legal holds, and compliance requirements.
• Administer Exchange/M365 auditing, message tracing, and forensic analysis.
• Implement and maintain DKIM, DMARC, SPF, MFA, conditional access, and secure mail flow.

Operational & Project Leadership

• Troubleshoot advanced messaging issues across hybrid environments.
• Lead upgrades, migrations, and modernization efforts.
• Coordinate cross-team initiatives involving security, networking, and identity.

Documentation & Process Improvement

• Maintain detailed system documentation, diagrams, and SOPs.
• Improve operational workflows and knowledge base content.

Education and Experience

• 6+ years of experience in enterprise messaging administration or equivalent.

Preferred certifications

MCSE Messaging, M365 Messaging Administrator, Security Administrator.

Knowledge, Skills, and Abilities

• Expert proficiency in Microsoft Exchange (on-prem and cloud).
• Deep knowledge of Exchange hybrid architecture and troubleshooting.
• Strong proficiency with Microsoft 365 services including Teams, SharePoint, and Power Platform.
• Expertise with Proofpoint administration and mail hygiene solutions.
• Strong PowerShell automation skills for Exchange and M365.
• Understanding of PKI, SMTP, DNS, certificates, and encryption.
• Excellent communication and documentation skills.

Work Environment

Typical office environment with moderate noise levels.

Physical Demands

Ability to remain in a stationary position for prolonged periods.

Frequent computer use and communication with staff and leadership.