Hello Gordon. To disable Outlook's junk mail filter in Classic Outlook for Windows, follow these steps:
Open Outlook and the Home tab.
Select Junk > Junk E-mail Options.
In the dialog box that opens select No Automatic Filtering. This disables Outlook's built-in junk filter but messages coming from Blocked Senders may still be moved to Junk.
- To ensure your filtering is entirely disabled, go to the Blocked Senders tab and click Remove for all addresses.
The above steps will stop Outlook from automatically moving emails to Junk. You may also have other spam filter running, for example, antivirus or other third-party add-ins, which may also redirect email delivery.
Here's the reference: How do I turn off junk mail completely in the latest version of Outlook?
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