I like the 200° oven idea. That temp will kill pretty much anything. I was thinking of using a no rinse sanitizer, like Star San, or even some of the brewery grade stuff I have access to at work. Just didn’t know if it was worth the effort. I’ve been on the pipe less than a year & haven't developed a deep cellar yet.I either, put old jars in the oven at 200F for 30 minutes or so before packing... after cleaning with soap of course. Or, I will soak them in the sanitizer I use for bottles when corking wine. It is called One Step, but you could use a little bleach poured into your hot water in the sink. Just soak them and let them drip dry. Don't wipe with a cloth, because that will negate all of your efforts.
New jars come sterilized, so I just use them as is.
From what I’ve gathered in this thread, mold or unwanted microbes aren’t overly common. They just happen by chance. However, I live in the Deep South, where mold grows on anything standing still for 20 min.