SharePoint Workspace supports two methods of assuring the identities of your contacts: administrator and manual verification. ...

SharePoint Workspace supports two methods of assuring the identities of your contacts: administrator and manual verification.  Some contacts may be verified by company administrators, providing a level of assurance that the identity is valid.  You can also manually verify the identities of any of your contacts, for example by directly verifying the contact's digital fingerprint with the person assuming that identity.