You can upload Outlook items - appointments, meetings, contacts, tasks, and posts - to SharePoint.
By default, Outlook items uploaded to SharePoint receive the message icon (), because they are .msg documents.
To assign the correct icon to uploaded Outlook items:
The MessageClass column must be added to the SharePoint library and to the content type assigned to email messages:
- Create a column called MessageClass in the SharePoint library.
- Set Column type to Single line of text.
- Uncheck Add to all content types (recommended).
- Uncheck Add to default view, in order to hide the column from the library view (recommended).
- Add this column to the content type assigned to email messages.
- Select the column from the content type and set This column is to Hidden, to hide the column from the document properties (recommended).
Read the article Map email headers to SharePoint metadata for more information.