For the good people here on PL who leave their properties locked down and shut up for long periods, then return to find that horrible mould and musty smell issue, the suggestion by robf above is well worth looking into.
Alternatively, if you don't have a trustworthy neighbour who will open front and rear doors for an hour or two each week, in order to air the place, then I've thought of another possible solution...
All internal doors left wide open. A Dehumidifier unit powered from a smart Timer plug, that kicks in nightly at (say) 21:00 for an hour, or perhaps weekly for a couple of hours?
From an external security point of view, it's well worth considering LED Dawn to Dusk lamps, front and rear. These cost peanuts to run leccy wise, but do alert low-life that someone is at home. You can also leave a low wattage LED table lamp running 24/7 (or on a daily timer plug) inside the property, to further deter potential burglars...
Thoughts please?
Cheers- AL

Gone but not forgotten...