emails dissappearing in outlook

Almost always the backing store server (where messages live) has both POP3 + IMAP4 enabled.

Then some people access the backing store using POP3 + delete messages on server.

Simple Fix: Disable POP3 + force everyone to only connect using IMAP4s (where s == TLS cert encrypted).

Another chance, You may have any filter enabled or a rule is set for this address. Please check them.

I knew I jumped the gun on asking this.  Someone DID delte the emails about 45 minutes ago from the inbox.  So, here is the question I still need answered:  How did they get into the recovered deleted emails folder so quickly?  What is the timeframe for an email to be deleted and then it goes to the deleted items folder and then to the recover deleted items folder?

Depends on the person's actions speed :)
He can delete the emails from inbox, then from deleted items (or even without moving to deleted items folder) as easy as 1..2..3.

They did not delete from the deleted items so the question is how long does it take for the deleted items to go to the recover deleted items folder?

The default retention policy for deleted items is 14 days. However, it can be modified. If interested reading, the below document explain the deletions specifically.
https://docs.microsoft.com/en-us/exchange/security-and-compliance/recoverable-items-folder/recoverable-items-folder#:~:text=The%20default%20deleted%20item%20retention,quotas%20later%20in%20this%20topic.

Regards

Still don't know how the deleted items entered the deleted items folder at around 9am this morning and by 9:30 they were already in the recover deleted items folder.

The user deleted the email and it goes to the 'Deleted Items' folder. The user again delete it from the 'Deleted Items' folder (or empty deleted items folder). This moves the email to recoverable folder. Here it will stay for 14 days by default.

But that is not what happened.  The user did NOT delete the email from the deleted items folder and it ended up in the recover deleted items folder.  How did this happen? 

Did you confirm that he didn't delete from deleted items folder? Then he must have used Shift+delete (holding shift key and press delete will skip moving to 'Deleted items' folder).

So shift+delete will go directly to the recover deleted items?

You found the answer! Thanks!  

Hey mkramer777,

It looks like you found the solution to your question! If anyone else faces a similar situation, here's a brief summary:

The issue was emails disappearing in Outlook, and it turned out they were being deleted by a user. The concern then shifted to how quickly these deleted items ended up in the "Recover Deleted Items" folder.

The answer provided was that the default retention policy for deleted items is 14 days. However, the crucial discovery was the use of Shift+Delete. If a user employs Shift+Delete, it bypasses the "Deleted Items" folder and directly moves the email to the "Recover Deleted Items" folder.

You can check this helpful blog for more insights: https://www.stellarinfo.com/blog/fix-outlook-folders-disappeared/