It depends on the mood of the prison staff at the time. Generally the mail gets to the right inmate if the number is correct, but if it is ever returned - we notify you and resend the corrected letter.
https://www.inmateaid.com/ask-the-inmate/what-happens-if-u-put-the-wrong-housing-unit-on-the-envelope.amp#answer
Accepted Answer Date Created: August 10,2013