C.R.S. § 1-7.5-203

At any time during the fifteen days prior to and including the election day, the county clerk and recorder or designated election official shall deliver to the counting place judges all the mail ballot envelopes received up to that time in packages or in ballot boxes that are locked and secured with a numbered seal, and the record of mail ballots as provided for in section 1-7.5-106.5 (3) for which a receipt will be given. The county clerk and recorder or designated election official shall continue to deliver any envelopes containing mail ballots that may be received thereafter up to and including 7 p.m. on election day.