When the email plugin gets called post-save, this code:
email.RegardingObjectId = new EntityReference(Incident.EntityLogicalName, caseId);
service.Update(email);
returns the following error:
"Cannot update subject or description unless email is in draft status"
I can simply use the following code in pre-save without error:
email.RegardingObjectId = new EntityReference(Incident.EntityLogicalName, caseId);
However, I would prefer to use post-save/asyncronous for better performance because I think putting the logic in pre-save will make the save operation longer as opposed to letting supporting processes run in the background, right?