EmailMessage object access in Case Trigger after insert

Question

Of course people will suggest to use EmailMessage trigger but if I update case from there then the problem is in case auto response rule as our requirement is mainly to fire the autoreply after the case trigger insert the case original recipient email.

Code

    trigger CaseTrigger on Case (after  insert) {
    
        List<Case> caselist = new List<Case>();
    
        EmailMessage emailMsg= [SELECT ToAddress  FROM EmailMessage 
                                 WHERE ParentId IN : trigger.newMap.keyset() ];
                               //this says no Sobject error
    
        for(Case caseData : trigger.new)
        {
            
            Case origcase = new Case(Id=caseData.Id, Original_Recipient__c = '[email protected]'); //This will work.
    
            Case origcase = new Case(Id=caseData.Id, Original_Recipient__c = emailMsg.ToAddress); //This is not working.
            
            caselist.add(origcase);
        }
    
        update caselist;
        
    }

I want the email message ToAddress field value dynamically to set in case field.

Is there some trick to fix this problem? If it is not possible then we need to change a big infra for that, please help. thank you.

Answer 1

I know you probably have already found a workaround by now, but I think the primary issue if order of execution on insert (and what fields are set at each time).

From my understanding, when the email comes in, it does not have a relatedTo just yet because the Case has not been created. So then the Case gets created . Then once the Case finally has an Id (after insert) the EmailMessage is then updated with the RelatedTo (the Case Id).

I would in this case not rely on the auto-response rule when the 'Email Message: To Address' is important to you. I would potentially try using other specific criteria on the auto-response rule, or do something in other automation that can trigger on edit of that new Case/EmailMessage.

Found a similar question here: https://developer.salesforce.com/forums/?id=906F00000008z2HIAQ