21May 2026 by Ceyhun Kirmizitas 0 Comments
Force OWA Light Users to Premium OWA After Exchange Server May 2026 CVE Mitigation

Force OWA Light Users to Premium OWA After Exchange Server May 2026 CVE Mitigation

Exchange, Exchange Server SE / 2019 / 2016, Migration & Upgrade, Security & Hardening
Applies to: Exchange Server SE / 2019 Microsoft recently published guidance for Exchange Server addressing the May 2026 vulnerability. One important note in the article is related to OWA Light. Microsoft states that OWA Light — accessed by using an OWA URL ending with /?layout=light — does not work properly after the mitigation is applied. Microsoft also notes that this feature was deprecated several years ago and is not intended for regular production use. For a deeper look at the OWA request path and frontend/backend authentication design, see Exchange OWA Authentication Deep Dive – Part 1. This can become a practical issue if some users previously selected the following option in Outlook on the web: "Use the light version of Outlook" When this option is selected, the user may continue…
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18Mar 2026 by Ceyhun Kirmizitas 0 Comments
What Happens to Shared Calendars After Exchange Hybrid Migration?

What Happens to Shared Calendars After Exchange Hybrid Migration?

Exchange, Exchange Online, Hybrid, Migration & Upgrade
Applies to: Exchange Server SE / 2019 / 2016 | Exchange Online | Hybrid In Exchange Hybrid environments, shared calendar behavior after mailbox migration is often misunderstood. Calendar access does not automatically fail when a mailbox moves to Exchange Online, but the result depends on the permission type, how it was assigned, and the hybrid configuration. This article walks through a controlled test and shows the behavior observed before and after the move. In This Article 1. Scenario 2. Step 1 – Test Default Behavior (On-Prem → On-Prem) 3. Step 2 – Check Existing Permissions 4. Step 3 – Assign Explicit Permission 5. Step 4 – Verify Access 6. Step 5 – Migrate Mailbox to Exchange Online 7. Step 6 – Test After Migration (Both Directions) 7.1 Test 1 –…
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18Dec 2012 by Ceyhun Kirmizitas 0 Comments
Moved Mailboxes Appear as Soft-Deleted After a Database Move in Exchange Server

Moved Mailboxes Appear as Soft-Deleted After a Database Move in Exchange Server

Exchange, Exchange Server SE / 2019 / 2016, Migration & Upgrade
Applies to: Exchange Server SE / 2019 / 2016 After moving a mailbox to another mailbox database, you may still see the old mailbox on the source database with a SoftDeleted disconnect reason. This is expected behavior in Exchange Server, including Exchange Server Subscription Edition, Exchange Server 2019, and Exchange Server 2016. The mailbox on the source database is not another active copy of the user mailbox. Exchange keeps the source mailbox temporarily so that its data can still be used for recovery if something goes wrong after the move. In This Article 1. Why This Happens 2. Check Soft-Deleted Mailboxes 3. Check Mailbox Retention 4. Should You Delete It? 5. Permanently Purge a Soft-Deleted Mailbox 6. Key Takeaways 1. Why This Happens When a mailbox move between Exchange mailbox…
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09Sep 2010 by Ceyhun Kirmizitas 0 Comments

How to Install Exchange Server Updates on DAG Members

Exchange, Exchange Server SE / 2019 / 2016, High Availability, Migration & Upgrade
Applies to: Exchange Server SE / 2019 / 2016 / 2013 / 2010 Exchange Server updates on a Database Availability Group (DAG) should be installed one member at a time. The main goal is to move active databases away from the server, prevent them from activating back during maintenance, install the update, and then return the server to production. The original version of this article was written for Exchange 2010 SP1 and used the term Update Rollup. Current Exchange Server servicing uses Cumulative Updates (CU), Security Updates (SU), and when required Hotfix Updates (HU). The DAG maintenance principle is still the same. In This Article 1. Before You Start 2. Put the DAG Member in Maintenance Mode 3. Install the Exchange Update 4. Return the Server to Production 5. Update…
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