All Outlook messages saved to the SharePoint Flex site using the Plugin are stored in the Email Document Library.
To view or modify the contents of the Email Document Library, select Settings/Site contents:
Scroll down to locate the “Email” document library:
Ensure the following fields are in your Email list.
Subject
Sender
Recipient
Body
Number_x0020_of_x0020_Attachments
Sent_x0020_Date
Content Type
Also ensure the Email list has exactly the same fields set in below settings.
CompanyFieldName
MainContactFieldName