I think the CAA should at least maintain a separate "bulk mailing" address for the stuff they send out e.g., GASIL. I did ask and they said they can't.
It is easy enough to give them an address which affords the aircraft owner some privacy, but the single-address limitation means whatever address one gives them will have to pass on all the stuff.
Occassionally one receives (to the same single address) an invoice from some far away airport for some landing or parking fee which they allege (almost certainly incorrectly) was unpaid during a visit a year ago....