This element is required and identifies the
type of recipient. It is one of TO, CC, EXCLUDE, TO_ZEN, or CC_ZEN. The TO
value indicates the recipient should receive a copy at the message’s associated
action precedence (Message.PrecedenceList.ToPrecedence) while the CC value
indicates the recipient should receive a copy at the message’s associated info
precedence (Message.PrecedenceList.CcPrecedence). The EXCLUDE value indicates
the recipient is a member of a group which should not receive a copy of the
message and should only be used when the OrgType is GroupMember. The TO_ZEN and
CC_ZEN values indicate the recipient should not receive a copy of the message
because that copy was delivered to that recipient outside the organizational
messaging systems.