This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This page may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.
This property is one of the address properties for the message sender. It must be set by the outgoing transport provider, which should never propagate any previously existing values.
If no transport provider has supplied any sender address properties, the MAPI spooler attempts to fill them in by calling the IMAPISession::QueryIdentity method for an entry identifier. If no entry identifiers have been provided, the MAPI spooler stores a key corresponding to the string "Unknown" in this property.