When you raised a new case from an email, the case ID is not set and shows as [Empty ID].
If you have defined more than one allotment templates under Team Helpdesk Manager > Templates Manager > Allotment Template tab, and when you generate a new case from an email (Using the convert to case button), the case will not get a ID yet. At the same time, the email (copied to the Team Helpdesk > History folder) will have a random temporary ID (in the format THOALLO-XXXXX). This is because the actual case item does not have a unique ID yet. This is done so, so that you can choose a specific allotment template for that particular case before Team Helpdesk sends out the automated notification to the caller. When you have chosen an allotment template and save the case, a new ID will be set and at the same time, the email (in the History folder) will also be updated to show the new ID.
If you don’t want to specify an allotment template for new cases, you can set a default allotment template that will be used for every new cases under Team Helpdesk Manager > Case Options > Default Values tab > ‘Allotment template for new case’