Structures consisting of less than 10 blocks or without a core are considered "‘micro-structures’. If not ‘touched’(interacted with), these structures/vehicles will be deleted by the server after 6 hours.
2.215-Day Deletion Timer for Not ‘Touched’ Structures .
After 15-days, a structure not ‘touched’(interacted with) will be deleted by the server. You or others must minimally ‘touch’ a structure every 15-days to avoid deletion.
touch means literally standing on top of the structure or walking on the blocks. HWS Structure Commander (via HWS Connect) displays the number of days since a structure was last touched. Using the Control Menu ( P ) is NOT considered touching.
No, it is old. Since end of Alpha 10, begin of Alpha 11:
Auto Clean Up
ECC Planet and its Sector are very attractive – that attractive that players park their structures there and don’t even care about the Taxes. This is unfortunately not in the best interest of the whole community, because others have to render an unused structure.
So keep in mind that your structures are being removed from there if you did not warp with them in the last 7 days !