Q: Mail Folder Files, Office 365 no subject

Hello,

We use Office 365 as our mail system. Now my account has a Folder that contains only mails with attachments, no subject and the texts is without any spaces put together.

I can't delete the folder, gives the message it is needed by the server.

But it disturbs my search. And it keeps growing. It is only from mails that had original a attachment in it. The message is also in my inbox.

How to delete this folder.