3 个回答
Create a custom field on the Contact object.
You need to write a flow and call the flow from a process builder on emailmessage object upon creation, the condition to call the flow should emailmessage.incoming is false. Pass the emailmessageID to the flow as input.
In the flow get records for EmailMessageRelation object where:
1) EmailMessageId is the ID passed from process builder to the flow
2) RelationObjectType = Contact
This will give you IDs of the contact records you need to update, select the update element to set current date/time as the custom fields value.