Question about Outlook Express

I recently moved my domain's emails to Windows Admin Center and now access emails via outlook.com. I also use MS Office Outlook 2007 to access emails (using the POP3 server). 

I need to retain all my messages on the server so I checked "Leave a copy of the messages on the server". I found that every few hours Outlook 2007 would re-download all my 150 from the server. The only workaround that worked was to uncheck "Leave a copy of the messages on the server".

I now find that all my messages are going into a folder called POP in outlook.com - which is great because that serves my purpose. But the POP folder is nested under the Deleted folder.

My QUESTION:

Will outlook.com periodically delete all my emails from the POP folder? Or will the emails remain in the POP folder despite the fact that it is under the Deleted folder?

Many thanks