[HarryHirsch]

I thought it had been common knowledge that the way handwritten mail is sorted is that it is barcoded and photographed, and then the address is keyed on by a human.

It doesn't take much imagination that these days each such address is kept, and that the three-letter agencies have a sample of everyone's handwriting, in case it is needed.

[akira2501]

Only if the OCR couldn't process it, although the OCR has gotten a lot better so the "Remote Encoding Centers" see a lot less volume. You could always tell when your mail failed the OCR in the past because it would have a faint orange barcode printed on it -- this was used to track it through the human encoding system at the RECs.