> call it how you like > > it is a device making NAt because you machines address is > a local one and not your public and if this thing has a > however broken setup it may be the root-cause >
Ok. Sorry for my weak knowledge. The modem is actually provided by the ISP in this situation modem or upstream. I am sure, with your informations provided, it is clear that the problem is ISP blocking port 25. I will politely ask them to open my ports. It is not fair nor solution to spam blocking it anyway. It is also not fair to told it is open while blocking. This is another mis behaving people.