Hello Laurence,
I am not aware of any functionality in Astea Alliance to support e-invoicing which is sending/receiving invoices in structured digital format (XML/UBL, etc.) instead of PDF/paper, often directly integrated with tax authorities or networks.
As you are aware, this product is now in a life-cycle phase where new functionality will not be developed for the standard product through the remaining lifetime of the product.
Anything to support such functionality should be handled through a customization code change and/or perhaps interfacing the invoice data from Astea Alliance to another system which DOES handle e-invoicing. However, this will not be developed within Astea Alliance itself.