Hi

I have a working code which allows to me to send whatever is being attached to a case. However, although mail.setWhatid(caseId) clearly takes in the case id linked to the attachment being uploaded, the email activity is still not being saved in case activity history. Please advise.

List<Attachment> attList = [SELECT Id, CreatedDate, ParentId, Name, Body, ContentType, Parent.Name FROM ATTACHMENT WHERE Id in: trigger.newMap.keySet()];
    
    for (Attachment a : attList) {
        attachIdList.add(a.parentId);
    }   
    
    List<Case> caseList = [Select Id from Case where Id in: attachIdList LIMIT 1];   
    
    for (Attachment att : attList) {
        for (case c : caseList) {
            if (today.isSameDay(att.CreatedDate) && att.ParentId == c.Id) {
                caseId = att.ParentId;
                aAtt = att;
            }
        }
    }
    
    Messaging.EmailFileAttachment [] efaList = new List<Messaging.EmailFileAttachment> () ;
    Messaging.EmailFileAttachment efa = new Messaging.EmailFileAttachment();
    
    efa.setFileName(aAtt.Name);
    efa.setBody(aAtt.Body);
    efa.setContentType(aAtt.ContentType);
    efaList.add(efa) ;   
    
    Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
        
    mail.setSenderDisplayName 'Corporate Sales Support hehehe');
    
    if(efaList != null) {
        mail.setFileAttachments(efaList) ;
    }
    mail.setToAddresses(toAdd);
    mail.setWhatid(caseId);
    //mail.setTemplateId(et.id);
    mail.setPlainTextBody('hellos');
    mail.setUseSignature(false);
    mail.setBccSender(false);
    mail.setSaveAsActivity(true);
    Messaging.sendEmail(new Messaging.SingleEmailMessage[] {mail});