Thank you all for your answers.
However, I have a problem. And I am very sorry for that. I wrote my original post too fast and messed up the words vertical and horizontal. It should have been horizontal and not vertically mounted oil filters. :-(
Basically it looks like this:
http://www.messicks.com/techimages/7800-engine-filter.jpg
In the meantime I bought a filter and cut it open with a saw to see whats going on inside.
I have made the following conclusions:
On the engine block there is a threaded pipe (OUTLET) for the oil filter and a hole adjacent to the pipe which acts as the INLET for the oil filter. The position of the INLET hole has a major impact on oil spills.
I assume the following: During an oil drain an equilibrium will slowly establish within the entire filter. If the filter is old and clogged this might take a long time (because oil pressure is needed to move oil across the filter media itself). The bypass valve (if fitted) should have no effect on this. By equilibrium I mean that the oil level within the filter is the same on both sides of the actual filter media. Because the outlet pipe is in the middle of the filter, the oil will empty itself at least to the lower edge of the threaded pipe. But basically this means that the filter is still almost halfway filled with oil!!
But now there is one "joker": Where is the inlet hole located? If the inlet hole is located at the lowermost point directly below the outlet pipe, then the oil should drain to that level and almost emptying the entire filter. But, if this inlet hole is located anywhere else than the lowermost point, let's say on the same level of the outlet pipe, then it is unavoidable to spill almost ½ an oil filter down the engine block.
As I remember, this inlet hole is often not located very smart by the engineers who designed the engine block.
Punching holes in the filter for depressurzing should have no effect based on this analysis.
Anyone comment on that analysis?