Conflict Message Outlook 2010

System

Hello All,

When we send an email to a folder FileSite, the mail gets filed in the Sent Items of our mailbox but with a conflict message:

Conflict Message: Conflicting edits were made to this item. Open the item to resolve this conflict.

We have installed FileSite 8.5 update 3, EMM 8.5 update 3 with Outlook 2010.

When you disable the option "Cache Mode" in Outlook removes the error but I dont want apply this solution (Outlook slows down if turn off).

Please, you know any other solution?

Thanks very much

Regards