MS Outlook won't to preview attachments with specific file extensions

Question

On one PC I can't handle with opening previews of some files from attachment in Outlook 365.
This issue is only with one PC. Previews on another PCs are working well. All PCs are in same domain with same policies.
For now I have found this issue only with files with extensions JPG and XML.
Another extensions like PNG, BMP or DOCX, XLSX, PDF even LOG, TXT are working well.

Any idea how to fix it?

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Detailed problem description:

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Software:

Windows 10 Enterprise (21H2) 64-bit
Microsoft Outlook for Microsoft 365 MSO (16.0.13127.21656) 32-bit IrfanView 4.54 64-bit

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Screenshots:

Screenshot 1: Issue with Outlook - Error messages and temporary files folder

Screenshot 1 description:

Warning message instead of file preview:

"This file cannot be previewed. Try opening the file in the program in which it was created"

• This message above has appeared after first one-click on attached file.
• After first one-click the preview is not visible but JPG file is immediately downloaded to Outlook temporary folder.

Error message after double click on file:

Attachment Security Warning
Warning!
This file may contain a virus that can be harmufl to your computer. ...

• And second error message window has appeared after double click on attached file.

Screenshot 2: Well working Outlook - previewed attechment

Screenshot 2 description:

• Preview of attachments appears immediately after first one-click on it.
• After double click on BMP or PNG will appear a prompt window with three options (Open, Save, Cancel).

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What I've tried - my failed solutions:

I found some possible solutions on similar issues like I have. But nothing helped on my specific issue.

At example:

• Possible solution 1: Office-Trust Center - Uncheck all options in Protected View

I unchecked them but without effect. Of course, I quit Word and Outlook and after then I tested previews in Outlook.

• Possible solution 2: Delete content of temporary folder for Outlook

Location for Temporary files folder: C:\Users%username%\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook

• Possible solution 3: In the Windows change a default Photo viewer

I set IrfanView and Windows Photo Viewer between each other but without any effect.

• Possible solution 4: Outlook-Trust Center - turn on desired previewer

I didn't find any image or XML previewer here.

• Possible solution 5 - Via dcomcnfg (Win+R) check if it is set Default Auth.Level: Connect & Default Imper. Level: Identify

It was set right.

• Possible solution 6 - Uninstallation of IrfanView 64bit & Installation of IrfanView 32bit

At first I unninstalled IrfanView 64-bit, then I was set Windows photo viewer as default app for JPG, then I started Outlook but it didn't help.
As second I installed IrfanView 32-bit but it didn't help either.

• based on @Faery 's Possible solution 7 - start Outlook in safe mode and disabling all Add-ins

Like @Faery described in his comment. I started Outlook in safe mode in which the previews worked. So I disabled all Add-ins except one which was not possible to disable. But after start Outlook in normal mode the previews didn't work.

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Answer 1

Try Working in Outlook safe and check if it helps. To know how to start Outlook in Safe mode, follow the steps below.

Go to Start >Search box and type outlook /safe, then press Enter. If Outlook safe works as expected, disable the add-ins as suggested below:

a. Click on File menu.

b. Click Options.

c. Click Add-ins.

d. Click on Go button besides Manage: Com-Add-in.

e. Check if there are add-ins listed, clear the checkbox to disable them.

f. Close the Outlook and restart it.

Answer 2

I found this in my registry

Path: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Security\
String value: Level1Remove
Value data: .xml;.jpg

I'm pretty sure that this was a remain after my past debugging of similar problem with XML file attachment. Unfortunately I forget to delete that string and didn't notice that JPGs stopped working.
Screenshot of Registry Editor & Outlook XML attachment

Thank you with your assistance with resolving of issue which I created by myself :)