Microsoft 365 administration: quarantine, blocked senders, forwarding and OneDrive retention
For Microsoft 365 administrators and senior service desk staff. Work through admin tasks and problems Microsoft documents in detail: why a message sits in quarantine and who may release it, when to use the Tenant Allow/Block List or a submission, what happens when a user is blocked from sending (550 5.1.8) and how to secure a compromised mailbox before unblocking it, how automatic external forwarding is controlled, and what happens to a leaver's OneDrive and to deleted SharePoint sites. Concepts and vocabulary come from Microsoft Learn; menus move, so confirm in current documentation.
- Level
- Intermediate
- Length
- About 50 minutes
- Contents
- 3 lessons · 1 video · final exam
- Status
- Published · updated 2 Oct 2026
- Microsoft 365
Skills you'll practise
- Explain which quarantined messages users can release, request, or never touch, and how quarantine policies and notifications change that
- Choose between a Tenant Allow/Block List entry and an admin submission for a false positive, respecting the verdicts that can't be allowed directly
- Recover a sender blocked for outbound spam by securing the account first, following Microsoft's compromised account steps
- Predict the result of outbound spam forwarding settings combined with remote domains and mail flow rules, and read mailbox forwarding properties
- Describe the OneDrive deleted-user process and deleted site retention, and set up access delegation so a leaver's files reach the right person
Course outline
- 1.Microsoft 365 admin: quarantine, blocked senders, forwarding and OneDriveVideo · 2 min
- 2.Quarantine, quarantine policies and the Tenant Allow/Block ListLesson · 17 min
- 3.Blocked senders, compromised mailboxes and automatic forwardingLesson · 17 min
- 4.Leavers' OneDrive, deleted sites and storageLesson · 16 min
- 5.Microsoft 365 administration: quarantine, blocked senders, forwarding and OneDrive retention: knowledge checkKnowledge check · 16 questions
- 6.Final exam9 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- Microsoft Learn: Quarantined email messages in EOP and Defender for Office 365
- Microsoft Learn: Quarantine policies
- Microsoft Learn: Manage quarantined messages and files as an admin
- Microsoft Learn: Manage your allows and blocks in the Tenant Allow/Block List
- Microsoft Learn: Use the Submissions page to submit suspected spam, phish, URLs, legitimate email and attachments to Microsoft
- Microsoft Learn: Remove blocked users from the Restricted entities page
- Microsoft Learn: Outbound spam protection
- Microsoft Learn: Control automatic external email forwarding
- Microsoft Learn: Responding to a compromised email account
- Microsoft Learn: OneDrive retention and deletion
- Microsoft Learn: Restore deleted sites
- Microsoft Learn: Manage site storage limits
- Microsoft Learn: Enable archive mailboxes in Microsoft Purview
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