Recently for a customer of mine Outlook email started going to the RSS folder instead of the Inbox.
It didn’t happen all the time, but a majority of email was being delivered to RSS folder instead of the Inbox folder. We were not able to determine why some emails went one way and some the other way.
This customer was using Microsoft 365 for email processing and it was only happening on one email account for the organization.
There is no Outlook setting under Options when using Microsoft 365 to change where incoming email gets delivered.
The solution was to close down Outlook and use the Run command (Windows+R) and start Outlook with a “/cleanserverrules” parameter behind it;
Once this was run Outlook now behaved normally and all emails were delivered to the Inbox rather than the RSS Folder.