system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does the post office redirect your mail when you change addresses if the info is handwritten on envelopes?
gpt
The post office scans the address and uses optical character recognition (OCR) to digitize the address.  The computer then helps sort the mail to the correct destination and can apply any address changes.

If the writing is too poor/damaged then a person has a look and tries to make it out and sort the package manually.