I don't think Envoy is abandonware 'cos Heinz Wrobel shows still some activity and help (regarding Envoy on OS4.x systems and maybe even helps every now and then in the OS4 team...). Sadly there is no distributor at the moment (was it Schatztruhe in the old days?).
Try to get it through eBay (there I found my Envoy3 CD) or try to contact one of the still active Amiga resellers, maybe they still some remaining copy of Envoy3.