ActivityParty in Email Message

 An activity party represents a person or group associated with an activity. An activity can have multiple activity parties.

Activity Party Types

There are 11 activity party types in Dynamics 365 Customer Engagement (on-premises). The activity party type is stored as an integer value in the ActivityParty.ParticipationTypeMask attribute. The following table lists the different activity party types, the corresponding integer value for the ActivityParty.ParticipationTypeMask attribute, and the description.

Activity party type	Value	Description
Sender	1	Specifies the sender.
ToRecipient	2	Specifies the recipient in the To field.
CCRecipient	3	Specifies the recipient in the Cc field.
BccRecipient	4	Specifies the recipient in the Bcc field.
RequiredAttendee	5	Specifies a required attendee.
OptionalAttendee	6	Specifies an optional attendee.
Organizer	7	Specifies the activity organizer.
Regarding	8	Specifies the regarding item.
Owner	9	Specifies the activity owner.
Resource	10	Specifies a resource.
Customer	11	Specifies a customer.

Activity Party Types available for each activity

Not all activity party types are available for each activity in Dynamics 365 Customer Engagement (on-premises), except for a custom activity. A custom activity supports all activity party types. You can associate an activity party type for an activity by using the respective attribute of an activity. For example, to associate an Organizer activity party type with an appointment activity, you must specify a value or an array of values of the ActivityParty type in the Appointment.Organizer attribute.

To control which email address should be used for sending emails to the activity party, or for replying to emails from the activity party, set the ActivityParty.AddressUsed attribute.

The following table lists the activity party types that are supported for each activity, and the corresponding activity properties to specify those activity party types.

Activity entity name	Supported activity party type	Activity attribute
Appointment	OptionalAttendee Organizer RequiredAttendee	Appointment.OptionalAttendees Appointment.Organizer Appointment.RequiredAttendees
CampaignActivity	Sender	CampaignActivity.Partners CampaignActivity.From
CampaignResponse	Customer	CampaignResponse.Customer CampaignResponse.Partner CampaignResponse.From
Email	BccRecipient CcRecipient Sender ToRecipient	Email.Bcc Email.Cc Email.From Email.To
Fax	Sender ToRecipient	Fax.From Fax.To
Letter	BccRecipient Sender ToRecipient	Letter.Bcc Letter.From Letter.To
PhoneCall	Sender ToRecipient	PhoneCall.From PhoneCall.To
RecurringAppointmentMaster	OptionalAttendee Organizer RequiredAttendee	RecurringAppointmentMaster.OptionalAttendees RecurringAppointmentMaster.Organizer RecurringAppointmentMaster.RequiredAttendees
ServiceAppointment	Customer Resource	ServiceAppointment.Customers ServiceAppointment.Resources