Literacy in the Postal System

I'm getting rather concerned about the post office and their employees. I suppose it's good coincidence that I'm reading 'Going Postal' by Terry Pratchett at the moment.

I think my postman is illiterate, dyslexic, drinking on the job, smoking weed on the job and/or blind.

My house number is 27. I get both my next door neighbours' mail. So I put up my house number. Nice and big next to the mail box slot. I still get mail for #25 and #29.

I also get mail for #27. Only it's the wrong street. I get mail for 2/5, 2/1 and 2/9. I used to drop these wayward letters on my way out (or in). Now, I can't be bothered. To the residents of BU2, if you want your missing Astro Guide, it's probably with me.