The inmate will let you know. These letters are not like registered mail where someone signs for it. They are mailed into the facility and inspected by the staff. After they have decided that the mail is ready to be handed out to the inmates, they distribute it at "mail call". If the mail is rejected for any reason and is returned, we will investigate the reason and let you know possible remedies.
https://www.inmateaid.com/ask-the-inmate/how-do-i-know-inmate-received-mail-sent#answer
Accepted Answer Date Created: April 08,2016