I would suggest you use a different collection to store them in (like a DataTable). You can use a DataTable in your script and then create a LookupTable with the same column name and type and replace it with the DataTable from your script (lookupTable.ReplaceTable method). From there, you could iterate it. There's no easy way to create an OutlookMailCollection in an automation although it is possible. I would suggest you do it in a script.

To create it in an automation, the only way I found was to create an instance of it by rightclicking on a proxy object of that type (the RetrieveEmail method returns that type). From there you can call the Add method.