ETL files in Outlook Logging folder consuming large amounts of disk space

A PC running the latest Microsoft 365 apps was repeatedly running low on free disk space despite the user’s best efforts at housekeeping. A cursory look identified the disk was filling up due to 51,200KB Outlook ETL files (created every time Outlook is launched) building up in C:\Users\%user%\AppData\Local\Temp\Outlook Logging. Allegedly, Outlook files should be deleted after 5 days, but that is not what was happening. Similar, but smaller, files were created when the user launched Word, Excel etc.

It was established that logging was NOT enabled within Outlook (Options | Advanced | Enable troubleshooting logging – unchecked), and in order to prevent the log files being generated, we had to create the following registry keys:

Ensure no Office applications are running, then launch Registry Editor (regedit.msc) and add the following as required:

[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\Access\Logging]
“DisableDefaultLogging”=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\Excel\Logging]
“DisableDefaultLogging”=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\Outlook\Logging]
“DisableDefaultLogging”=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\PowerPoint\Logging]
“DisableDefaultLogging”=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\Publisher\Logging]
“DisableDefaultLogging”=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\Word\Logging]
“DisableDefaultLogging”=dword:00000001

You can add one or more of these depending on which application(s) are causing the main problem. Note that the full path didn’t exist so some keys had to be created.

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