Mitigating backscatter spam (avoid sending back NDRs to false addresses)

Hello,

While I am aware there are a number of ACLs that could be applied to Exim that would help mitigate backscatter spam (i.e. preventing Exim from sending out NDRs to false addresses), I'm concerned that any change may affect future cPanel/WHM updates, as well as possibly borking the stock cPanel/WHM Exim config too.

I had toyed with the idea of experimenting with SpamAssassin's vBounce ruleset, but local testing doesn't seem to yield good results.

Does anybody have any comprehensive solution to dealing with backscatter on a cPanel/WHM system that won't break anything and can also be deployed by customers or who may be looking to role this out on their own systems?

Many thanks,

Martyn