ActivityId on EmailMessage Object in Salesforce
We will get INSUFFICIENT_ACCESS_OR_READONLY when we set ActivityId on the EmailMessage record with RelatedToId other than Case Record. Sample Code: objEmailMessage.RelatedToId = '0018c000026ZmPmAAK';//Hard Coded Account Id objEmailMessage.ActivityId = '00T8c00003vrOJ5EAM';//Not supported ....