You can put Ireland at the top of the list, one postcode for every address, every house has one, every apartment has one, every building has one, even some old ruins have one.
Your man Henderson
That boy with the glasses
who is doing a PhD up
here at Queen's in Belfast.
Buncrana
Co. Donegal
Ireland
I worked as a postie for a few weeks as a Christmas job when I was at Uni a looong time ago.
My GF used to write to me regularly (yes, writing letters was a thing back then), we came up a nice scheme: instead of using my actual address she wrote to a made-up non-existant address but with a valid postcode ("501 Any Street, Town, AB1 1AB" on a street with only a dozen houses) that was in one of the streets I'd be sorting letters for/delivering to.
Worked like a charm, would find her letter waiting for me in the pile to be sorted when I rocked up at the sorting office at 5am.