To display MLS ID's with your property, start by navigating to the property panel in the email editor, and click on it to make it active. From here:

• From the panel editing toolbar, select options
• Within the Layout sub menu, select the Select an item to add dropdown, and choose MLS ID.
• Click the add button.
• Change the order of the items if desired, using the up and down arrows.
• Select Continue

Your property panel will update to show MLS ID's within your new Property Details Layout