It's a mechanic that as far as I know was never implemented. Which is really disappointing because on my server in Ward 1 Mist there are a couple of abandoned houses. From what I understand, if your house was abandoned all your stuff would get mailed to you or some NPC would hold your junk for when you logged back in, if ever.

People can complain about how its something they paid for in game and that content shouldn't be taken away because every hypothetical of why you may not play and come back. Really though, housing is such a pain on some servers right now because of the limited space. A system like this should be implement for those who are actually take advantage of it.