German Valdez wrote:

In that case you would be blocking all the networks in 29 economies in Latin american and caribbean region.

The people doing this generally know this. They often also block big chunks of APNIC too. They often believe that the ratio of legitimate mail to spam coming from these networks for their customers is too poor to not block. They'll usually whitelist an address if one of their customers requests it. I'm not condoning the practice; I find it too extreme for my tastes. But there are a number of people doing it. Do a search at groups.google.com for "LACNIC group:news.admin.net-abuse.email" to see what people are saying/blocking. Bob