Yes, I do have pictures of both before and after. I didn't think of taking the exact same pictures though. Like when I moved in there was a crack in the linoleum in one of the bathrooms. I didn't take another picture of that same crack when I moved out. It hadn't gotten worse though, looked the same, so I didn't think there was a point to it.
I didn't make a detailed list of the problems at move-in. The landlord never did a walkthrough on move-in because they were still installing a few items at the time and then just never came back. It was a whole cluster then and seems to be a cluster now. Very irritating. I contacted them about numerous problems I found after move in; one of the bedroom doors wouldn't shut tight because the door was hung where the latch didn't meet the plate on the wall (don't know how to explain that better), one of the outlets flat out wouldn't work (they declined to fix it saying it was "too much of a hassle"), the faucet in the bathtub kep running (not just a drip, but steady stream. I did make them come out to fix that because it was making my water bill outrageous but the problem kept coming back every few months and would take them at least a month before sending someone again to fix it), things like that. Oh, not to mention that the night I moved in I had to call the gas company because of a leak. The technician that came said he was surprised there hadn't been an explosion because he could smell the gas from the street. He found the leak, the person who installed the stove put it in wrong. I found out later the person hadn't been certified to install gas appliances, even though according to the technician they were required by law to be because it was gas. Overall it was just a nightmare. I'm glad I got out of there finally. Now to clean up this mess and move on with my life.
Colorado's law only says that a written notice must be mailed. Their testimony that this was handled in the normal course of there business should be enough to show that it was mailed. Joe Crandall's suggestion that you obtain a copy of the statement is valid, but you can ignore his advice that you can claim treble damages in this case. The LL has already told you that the statement was mailed and that you still owe money, and they will testify to that in court.
Did you provide the landlord your forwarding address when you moved? If not, then the LL could have met the legal requirements by simply sending it to your last known address (the unit you were renting.)