Missing packages from the building

[Bocondo Williams]

I own a building with 15 units with mostly students as residents and we get new residents every year like all student housing. Aug bring new students and suddenly we have spike in missing packages and mails. USPS and other delivery guys mostly deliver mail at one location only near mailboxes, but in once in a while some case Prime or different delivery person will drop packages outside the building also, because they may not have access code to the building. We have security cameras in hallways so we can see who picks up the packages.

After receiving the complaints we send emails to all residents not to pick anyone else's mail or packages, but we still getting missing package complaints. As landlord/property manager what else we can do?