When uploading email messages to SharePoint, the email headers (From, To, CC, Subject, Date, etc.) can be automatically mapped to SharePoint columns. To enable this mapping, the SharePoint document library needs to be set up with email specific columns. To learn how to do this, read the knowledge base article Save email headers in SharePoint.
Note: When uploading an email message with attachments to a library with column validation (in SharePoint 2010 or later), and simultaneously replacing attachments with links, the email headers are not persisted as SharePoint document properties.
The mapping between email headers and SharePoint fields is configurable from the mapping table in harmon.ie Options.