Moving Office 365 Mailboxes to IMAP Servers - What’s the Best Approach
I’ve recently been looking into scenarios where organizations need to move mailboxes from Microsoft 365 to IMAP based email servers, and I noticed this is still a common requirement in many migrations. In most cases, the challenge is not just moving emails, but making sure everything like folder structure, old emails, and user data stays intact without creating too much disruption for users. From what I’ve seen, doing this manually can get very complex, especially when there are multiple mailboxes or large data volumes involved. That’s where migration tools usually come into the picture. Most tools simplify things by handling: 1. Secure connection to Microsoft 365 accounts 2. Bulk mailbox migration 3. Preserving folder hierarchy 4. Reducing downtime during the move 5. Avoiding duplicate data issues One thing I’ve noticed is that running a small pilot migration first always helps. It gives a clear idea of how the actual migration will behave before moving all users. Has anyone here worked on Office 365 to IMAP migration at scale? Would be good to know what approaches or tools worked best in your case and what challenges you faced during the process.Office 365 Mailbox Export to PST - Third Party Tools: What’s Your Experience?
Exporting Office 365 mailboxes to PST is still a common requirement in many Microsoft 365 environments, especially for backup, compliance, and migration scenarios. While Microsoft offers native options like Purview eDiscovery and Outlook export, many administrators also consider third-party tools when dealing with large mailboxes or bulk export requirements. In real-world scenarios, factors like speed, ease of use, permission handling, and consistency of exported data often influence the choice of tool. Some teams prefer native methods for compliance control, while others explore third-party solutions to simplify large-scale or repeated export tasks. For those working with Microsoft 365, what has your experience been with third-party PST export tools? Have they helped in your environment, or do you still rely mainly on Microsoft’s native options?
Prevent Microsoft 365 meeting invites from automatically appearing in users’ calendars
Hi All, We are trying to prevent Microsoft 365 meeting invites from automatically appearing in users’ calendars as Tentative until the user explicitly accepts the invite. Setting for Outlook Classic, New Outlook and Windows or Outlook Web. Need Microsoft recommendation on this one.Microsoft Issues Updated Guidance for Defender for Office 365 Licensing
Some inconsistencies in the MDO P2 service description and licensing terms exposed a need for tenants to license every user and shared mailboxes. Microsoft has changed the service description and licensing terms to make them simpler. Mailboxes still need MDO licenses, but only if they benefit from MDO protection, including MDO P2 if that’s what they use. Tenant admins have some extra work to do to deploy policies. All explained here. https://office365itpros.com/2025/10/31/mdo-p2-licensing/
Compliance licenses at tenant level
Hi, We are a small organization of about 200 employees, and we have following requirements. DLP policies configuration at Exchange, OneDrive, SharePoint BYOD security Users should not be able to send files outside the org And so on as we evaluate We already have M365 Business Premium. However, after researching we figured out that M365 Business premium will alone not solve our requirements. May be compliance license will. We want to apply security policies at tenant level in our organization but definitely do not want every user to get licenses as this will be expensive for us and there is no requirement at all for our users. The question is, Is there a way to solve the above scenario?Disable Direct Send in Exchange Online to Mitigate Ongoing Phishing Threats
Direct Send allows devices and applications to send unauthenticated emails over port 25 directly to Exchange Online. While this may support legacy devices like printers or scanners, it also opens the door for threat actors to deliver spoofed emails without authentication. These messages often appear to come from trusted internal sources, making them especially dangerous. To reduce your organization’s exposure to this threat, it's strongly recommended to disable Direct Send using Microsoft’s newly introduced RejectDirectSend setting. You can quickly enable this setting using PowerShell: Connect-ExchangeOnline Set-OrganizationConfig -RejectDirectSend $true If you still have devices or applications that need to send emails, use authenticated SMTP submission or set up connector-based routing with certificate or IP restrictions.The Art of Corporate Domain Rebranding in Microsoft 365: Technical and Compliance Challenges
Introduction Corporate domain rebranding is often perceived as a simple marketing change — a new name, refreshed logo, and website updates. However, within Microsoft 365 environments, rebranding becomes a complex technical operation impacting identity systems, authentication, collaboration tools, compliance archives, and user experiences. Having led multiple major domain rebranding initiatives, I’ve uncovered strategic and technical challenges organizations must anticipate, along with best practices to ensure seamless transformation. Key Technical Challenges in Domain Rebranding 1. Email Identity and Legacy SMTP Preservation Every user, shared mailbox, and distribution list must be readdressed, preserving historical SMTP aliases for continuity and legal compliance. Reference: https://learn.microsoft.com/en-us/exchange/email-addresses-and-address-books/email-address-policies/email-address-policies 2. OneDrive for Business and SharePoint Online URL Dependencies Rebranding requires careful planning for OneDrive and SharePoint URLs, tied to the tenant’s primary domain. Microsoft now supports renaming SharePoint domains — a feature I implemented to transition from legacy SharePoint domains to new branded domains using PowerShell and Microsoft’s supported process. Reference: https://learn.microsoft.com/en-us/sharepoint/change-your-sharepoint-domain-name 3. Authentication and Directory Synchronization Impacts When using Microsoft Entra Connect (Azure AD Connect), all User Principal Names (UPNs) must be adjusted to reflect the new domain, ensuring no disruptions to hybrid synchronization or Conditional Access policies. Reference: https://learn.microsoft.com/en-us/entra/identity/hybrid/connect/how-to-connect-sync-staging-server 4. Microsoft Teams and External Federation Teams relies on domain-based routing. Updating the primary domain affects federation trust and meeting invitations, requiring proactive partner communication. 5. Compliance and eDiscovery Integrity Archived content in Exchange Online, SharePoint, and Teams must maintain legal hold continuity and eDiscovery searchability, even after email addresses change. Reference: https://learn.microsoft.com/en-us/microsoft-365/compliance/ediscovery 6. Office 365 Apps: Identity, Activation, and Licensing Breaks Apps like Outlook, Teams, Word, Excel, and OneDrive cache user credentials and domain suffixes. Rebranding can cause: Activation failures Sign-in errors in Outlook or Teams Cached credential conflicts Strategic Solutions and Best Practices 1. Dual SMTP Strategy Add the new domain as the primary SMTP, retaining previous addresses as secondary aliases to maintain continuity, customer service, and compliance. 2. OneDrive and SharePoint Communication Plan Prepare user communication plans, support documentation, and staged URL testing before renaming SharePoint Online domains. 3. UPN and Sign-In Alignment Sequence UPN updates carefully in hybrid environments, testing Conditional Access, SSO, and MFA in staging before deployment. 4. Teams External Federation Refresh Inform external partners of domain changes, validate federation re-establishment, and update meeting templates. 5. Maintain eDiscovery Chain of Custody Document every mailbox address change. Confirm Microsoft Purview holds and content searches remain intact for both old and new identities. 6. Office 365 Apps Rebinding Strategy Communicate expectations clearly Instruct users to sign out before cutover Push credential cache clearing via script or Intune Re-authenticate apps post-UPN change Lessons Learned Rebranding is an identity transformation, not just cosmetic. Office apps can silently break; proactive reconfiguration avoids support spikes. Testing is non-negotiable. Communication reduces user friction and IT escalations. SharePoint domain renaming works with precision when following Microsoft’s official process. Conclusion Corporate domain rebranding in Microsoft 365 is a delicate balance of technical precision, compliance management, user experience preservation, and Office app continuity. Done correctly, it strengthens organizational agility and brand alignment without sacrificing trust. Cloud identity is brand identity — and managing it well is an art. About the Author Gonzalo Brown Ruiz is a Senior Microsoft 365 Engineer and Cloud Security Specialist with over 21 years of experience delivering secure, compliant, and resilient cloud environments across North America and Latin America. Specialized in Microsoft Teams, Exchange Online, OneDrive for Business, SharePoint Online, Microsoft Purview, and Entra ID.
