For college students living out of state, if they haven’t returned their ballot, PLEASE tell them to vote and go inside USPS and ASK FOR A POSTMARK stamped on their return envelope. They do not need to pay for stamps, but to ensure that it will count, I highly recommend asking for a postmark.
USPS is not required to and are not in the habit of putting postmarks on pre-paid mail. Unless it is specifically asked and requested, they won’t do it.