Senior M365 Engineer

Online, email security and delivery

• Manage Exchange Online, including hybrid
• Exchange, mail flow, connectors and migrations.
• Configure email security: SPF, DKIM, DMARC,
• Defender for Office 365 and anti-phishing policies.
• Own resolution of email delivery issues: bounces and NDRs, delayed or missing mail, messages wrongly sent to junk or quarantine, and inbound/outbound blocking.
• Investigate with message trace, message headers, quarantine and Exchange admin center reports.
• Monitor sender reputation and handle blocklist delisting (e.g. Microsoft, Spamhaus) and third-party mail gateway or relay issues.
• Manage DNS records for mail (MX, SPF, DKIM, DMARC, Autodiscover) and review DMARC reports to prevent spoofing and delivery failures.

SharePoint and OneDrive

• Administer Teams, including policies, governance, Teams Phone and meeting rooms.
• Design SharePoint Online and OneDrive structure, permissions, sharing and lifecycle policies.

policies, identity and compliance

• Design, implement and maintain Microsoft 365 security policies aligned to Microsoft and CIS security baselines.
• Configure Defender for Office 365 policies: Safe Links, Safe Attachments, anti-phishing, anti-spam and anti-malware.
• Enforce Conditional Access policies: MFA for all users, blocking legacy authentication, and location and device-compliance rules.
• Set external sharing, guest access and Teams/SharePoint security policies.
• Configure audit logging, alert policies and app protection policies for Outlook and Teams on mobile devices.
• Administer Entra ID: hybrid identity (Entra Connect), Conditional Access, MFA and PIM.
• Implement Microsoft Purview: data loss prevention, sensitivity labels, retention and eDiscovery.
• Monitor and improve Microsoft Secure Score and respond to security alerts.

• Automate administration and reporting with PowerShell and Microsoft Graph.
• Manage licences, service health, change management and vendor support cases.
• Keep documentation, runbooks and user guidance up to date.

• 7+ years in Microsoft infrastructure, including 5+ years administering Microsoft 365 at enterprise scale (1,000+ users).
• Proven experience leading Exchange and tenant-to-tenant migrations.
• Deep knowledge of Exchange Online, Teams, SharePoint Online and OneDrive.
• Strong Entra ID, Conditional Access and hybrid identity experience.
• Hands-on experience with Purview compliance and Defender for Office 365.
• Strong PowerShell skills, including Microsoft Graph.
• Experience leading projects, mentoring engineers and working with senior stakeholders.
• Proven track record troubleshooting complex email delivery issues using message trace, headers, NDR codes and DNS mail records.
• Hands-on experience designing and implementing Microsoft 365 security policies (Defender for Office 365, Conditional Access, sharing and audit policies) in an enterprise tenant.

Security / compliance