Post-Migration Checklist: What IT Teams Must Do After Moving to Microsoft 365

Completing a Microsoft 365 migration doesn’t mean the job is done. Post-migration tasks are just as critical as the move itself. If you overlook these steps, users may face issues with mailbox access, service availability, or compliance violations. A structured post-migration checklist ensures everything is functioning as expected and nothing is left unaccounted for.

This guide walks through the key tasks IT teams must perform immediately after migrating to Microsoft 365.

Post-Migration Checklist: What IT Teams Must Do After Moving to Microsoft 365


1. Verify Mailbox Integrity and Data Consistency

After migration, verify that all user and shared mailboxes have migrated successfully. Randomly check sample mailboxes to ensure folders, email threads, attachments, and calendar entries are intact. Look for missing items or corrupted messages using content comparison reports.

Use:

powershell

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Get-MailboxStatistics -Identity "user@domain.com"

Compare item count and size with pre-migration logs to ensure consistency.

2. Confirm DNS Record Updates

Once the cutover is complete, DNS records must point to Microsoft 365. This includes MX, Autodiscover, and SPF entries.

Check:

  • MX record → Points to domain.mail.protection.outlook.com
  • Autodiscover → Validates proper Outlook configuration
  • SPF → Includes include:spf.protection.outlook.com

Use online tools or PowerShell to verify DNS propagation across regions.

3. Reconfigure Outlook Profiles

Old Outlook profiles may still refer to legacy server settings. Users should recreate their Outlook profiles to avoid caching or sync errors.

For enterprise environments, deploy Outlook profile reset scripts via Group Policy or Endpoint Manager to automate the process.

4. Reassign Permissions on Shared Mailboxes and Calendars

Permissions assigned in legacy systems may not carry over during migration. IT teams should verify and reapply delegate access, calendar sharing rights, and mailbox permissions using PowerShell.

Examples:

powershell

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Add-MailboxPermission -Identity "Shared" -User "John" -AccessRights FullAccess

Add-MailboxFolderPermission -Identity "Shared:\Calendar" -User "John" -AccessRights Reviewer

5. Review Mobile Device Access

Re-authentication is required for mobile apps post-migration. Inform users to remove and re-add their Microsoft 365 accounts on Outlook Mobile. This clears stale tokens and ensures sync with the new tenant configuration.

Use Conditional Access policies to restrict or monitor mobile access.

6. Validate OneDrive and SharePoint Sync

For users migrated from on-prem or hybrid environments, verify OneDrive and SharePoint Online libraries are syncing correctly. Use the OneDrive admin portal to review user activity and sync errors.

Ask users to open and test shared files or links to ensure permissions are intact and versioning is working.

7. Check Retention Policies and Compliance Settings

Post-migration is the right time to enforce Microsoft Purview features. Review retention tags, eDiscovery holds, and mailbox auditing.

Enable mailbox auditing for all users:

powershell

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Set-Mailbox -Identity "user@domain.com" -AuditEnabled $true

Also, ensure users from regulated industries have appropriate DLP and sensitivity labels assigned.

8. Monitor Service Health and User Feedback

Use the Microsoft 365 admin center to monitor service health, latency, and mail flow. Set up alerting for unusual activities and failed logins. Actively collect feedback from end-users to identify access issues or degraded performance early.

9. Disable Legacy Systems and Decommission

Once all checks are complete, decommission old mail servers, backup systems, and connectors. But keep backups for a defined period as per compliance requirements. Archive logs and reports from the migration process for future audits.

10. Document Everything

Create documentation of your Microsoft 365 environment. Include user permissions, DNS settings, applied policies, and third-party integrations. Good documentation supports future troubleshooting and scaling.

Final Note

Post-migration work is about making the environment reliable, secure, and user-ready. IT teams should not consider the project complete until every element has been validated.

To make this process more manageable, tools like EdbMails Office 365 Migration tool not only handle the migration but also offer detailed post-migration reports. These reports help you verify mailbox consistency, check for skipped items, and reduce manual effort during validation.

Use automation wherever possible and maintain a checklist-driven approach to avoid blind spots after your Office 365 migration.

Location: United States

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