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What is your account? Outlook.com or something else?
Does the issue occur recently on Outlook Desktop Client? Do you have any specific operation before the issue occurred?
What is the version of your Outlook? It is recommended that you please check the Outlook client version (File>Office Account>Product Information) and try to upgrade to the latest version to see if the problem is resolved.
In addition, here are some steps you may take:
- Check Email Security Settings:
- Go to File>Options>Trust Center>Trust Center Settings>E-mail Security.
- Ensure that "Read all standard mail in plain text" is unchecked.
- Adjust Trust Center Settings:
- Go to File>Options>Trust Center, Trust Center Settings.
- Under Automatic Download, uncheck the box that says, "Don't download pictures automatically in HTML e-mail messages or RSS items".
More information: Block or unblock automatic picture downloads in email messages - Microsoft Support
Hope it helps!
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