I'm looking for some network that offering high volume
Thanks 
I have zero expertise on the subject however I have adplexity pulled open and it looks like 21k ads in Italy for Outbrain, and 2-3k each for MGID, Revcontent, and Taboola 
Just a hunch but for actual Italian sites that only Italians visit, I would think MGID might have the biggest presence, but that's totally speculation. I would imagine any of the those four will give you plenty of traffic though in Italy.
I'm running with MGID and Rev, Taboola and Outbrain are very strict for my product.
have you ever heard about the 4w marketplace?
I haven't... is it a non-US one or?
Taboola and Outbrain do seem quite strict. I do notice some very racy ads on Adplexity from their networks on obscure geo's sometimes but from everything I've heard their compliance is generally much more strenuous than Revcontent and MGID.