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Senior Exchange Online (EXO) Administrator

System One Holdings, LLC

Posted today

Job Requirements

Washington, DC
Public Trust Polygraph not specified
Career Level not specified
Salary not specified
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Job Description

Senior Exchange Online (EXO) Administrator
Washington, DC –100% onsite
Per Federal contract U.S. citizenship is required
Must be able to obtain Public Trust clearance
Open to W2 and C2C
Must apply by June 30th

Position Summary:
Manage and maintain our hybrid Exchange environment, including on-premises Exchange Server and Exchange Online (Microsoft 365). Ensure reliable email services, security, and compliance across the organization.

Key Responsibilities:
• Administer and support hybrid Exchange infrastructure (on-premises and Exchange Online)
• Manage mailbox migrations, mail flow, and hybrid connectivity between environments
• Configure and maintain transport rules, DLP policies, retention policies, and email security features
• Monitor system performance, troubleshoot issues, and resolve user email problems
• Implement anti-spam, anti-malware, and threat protection using Microsoft Defender for Office 365
• Manage user provisioning, distribution groups, shared mailboxes, and permissions
• Maintain hybrid synchronization and directory services (Azure AD Connect)
• Execute eDiscovery, legal holds, and compliance investigations
• Document configurations, procedures, and maintain system architecture records
• Provide end-user support and training on email features

Required Technologies
• Microsoft Exchange Online & Exchange Server (hybrid environment)
• PowerShell (Exchange Online/On-Prem Management)
• Microsoft 365 Admin Center & Exchange Admin Center (EAC)
• Azure Active Directory & Azure AD Connect
• Exchange Online Protection (EOP) & Microsoft Defender for Office 365
• DNS, SPF, DKIM, DMARC, mail flow routing

Required Experience
• 4+ years managing Exchange environments
• 2+ years with hybrid Exchange (on-premises + Exchange Online)
• 2+ years PowerShell scripting for Exchange administration
• Hands-on experience with mailbox migrations and hybrid deployments
• Email security and compliance implementation

Preferred Qualifications
• Microsoft 365 Certified: Messaging Administrator Associate
• Experience with 500+ user environments
• ITIL or service management experience
group id: 10295162
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About Us
System One is a leading provider of specialized, highly technical outsourced services, workforce solutions, staffing, and recruiting to critical infrastructure, technology, life sciences, and government sectors As an essential partner to private and public organizations of various needs and sizes, we offer our expertise to help them bring their most complex and mission-critical programs to fruition. With our highly specialized services, in-demand technical skills, and vast operational expertise, we can deliver accelerated results that benefit our clients and the job seekers who partner with us.

System One Holdings, LLC Jobs


Job Category
IT - Software
Clearance Level
Public Trust