SQL Server 2025 CU1 and SQL Server 2022 CU23: Critical Database Mail Bug – What You Need to Know

The Issue

If you’ve recently updated your SQL Server environment, you may have encountered a frustrating problem: Database Mail has stopped working entirely. Microsoft has confirmed a critical bug affecting both SQL Server 2025 CU1 and SQL Server 2022 CU23 that breaks the Database Mail functionality.

The error message you’ll likely see is:

Could not load file or assembly 'Microsoft.SqlServer.DatabaseMail.XEvents, 
Version=17.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91' 
or one of its dependencies. The system cannot find the file specified.

For SQL Server 2022, the version number in the error will show 16.0.0.0 instead.

Why This Matters

Database Mail is a critical component for many organisations. It powers:

• Automated alerting from SQL Server Agent jobs
• Monitoring notifications for performance issues and failures
• Scheduled reports delivered via email
• Backup completion notifications
• Security alerts for failed login attempts

When Database Mail fails, your entire alerting infrastructure goes silent. Jobs may fail without notification, critical issues go undetected, and your team loses visibility into database health.

What Happened?

The cumulative updates shipped with a dependency on a DLL file (Microsoft.SqlServer.DatabaseMail.XEvents.dll) that doesn’t exist in the installation. The DatabaseMail.exe process attempts to load this assembly and fails immediately, preventing any emails from being sent.

Microsoft has acknowledged the issue and temporarily pulled both updates from the download centre. The official documentation now states:

“This update is temporarily unavailable for download because of a known issue related to Database Mail.”

How to Check If You’re Affected

Run this query to check for unsent emails stuck in the queue:

sql

SELECT 
    mailitem_id,
    profile_id,
    recipients,
    subject,
    send_request_date,
    sent_status,
    sent_date
FROM msdb.dbo.sysmail_allitems
WHERE sent_status <> 'sent'
ORDER BY send_request_date DESC;

If you see emails with a status of ‘unsent’ or ‘retrying’ that aren’t being delivered, and you’ve recently applied CU1 (SQL 2025) or CU23 (SQL 2022), you’re likely affected.

Recommended Actions

Option 1: Uninstall the Cumulative Update (Recommended)

If you haven’t made other changes since the update, the safest approach is to uninstall the problematic CU:

1. Open Programs and Features (or Apps & Features)
2. Locate the SQL Server cumulative update
3. Uninstall and restart as required
4. Verify Database Mail functionality is restored

Microsoft provides detailed uninstallation guidance in their documentation.

Option 2: Wait for the Fix

Microsoft is working on a corrected update. If your environment can tolerate the temporary loss of Database Mail, you can wait for the patched CU to be released.

Option 3: File Replacement Workaround (Use with Caution)

Some administrators have reported success copying the Database Mail executables from a working pre-CU installation:

1. Stop Database Mail: EXEC msdb.dbo.sysmail_stop_sp;
2. Copy these files from a working instance’s \MSSQL\Binn folder:
   • DatabaseMail.exe
   • DatabaseMailengine.dll
   • DatabaseMailprotocols.dll
3. Replace the files on the affected instance
4. Restart Database Mail: EXEC msdb.dbo.sysmail_start_sp;

Important: This is an unofficial workaround. Document what you’ve done and plan to revert before applying future updates.

Lessons for Database Administrators

This incident reinforces several best practices:

1. Test updates in non-production first – Always apply cumulative updates to development or test environments before production.
2. Wait before applying new CUs – Consider waiting 2-4 weeks after a CU release to allow the community to identify issues.
3. Have a rollback plan – Know how to uninstall updates and ensure you have the ability to do so quickly.
4. Monitor your monitoring – Regularly verify that your alerting systems are actually working. A silent failure in Database Mail could leave you blind to other issues.
5. Subscribe to update notifications – Follow Microsoft’s SQL Server release notes and community resources like Brent Ozar’s blog for early warnings about problematic updates.

Timeline

• January 2026 – SQL Server 2025 CU1 and SQL Server 2022 CU23 released
• Within days – Community reports of Database Mail failures
• January 19-20, 2026 – Microsoft acknowledges the issue and pulls the updates
• TBD – Corrected updates expected

Need Help?

If you’re unsure whether your SQL Server environment is affected, or need assistance rolling back the update safely, our team can help. We provide remote SQL Server support across Australia and can quickly assess your situation.

Contact us for a free consultation.