There is nothing normal or standard behind the wall. The staff opens all of the mail, they inspect for contraband and they even will read the letters for content. Some even have "state laws" that require the mail held for up to 2 weeks. You will just have to be patient and understand that the control element of prison is the hardest part for anyone to adjust to - even for those on the outside.
https://www.inmateaid.com/ask-the-inmate/is-there-a-process-within-the-prison-that-holds-a-letter-back-a-few-days-longer-if-a-letter-took-3-days-from-my-place-to-the-facilityhow-much-longer-does-it-take-to-get-into-the-prisoners-hand#answer
Accepted Answer Date Created: October 23,2014