oops sorry I was just making sure you spoke dutch & posted in the correct section.
I do not speak dutch myself. If your english is ok, check the advice below.
Check the links I gave. There are tips on how to recognise common spam. Also some ways of blocking 'some' spammers. Generally ignore files below 2,000 KB (2 MB). And a few others above 2,000 KB to stay away from.