4.3 billion = 4 billion spammers and 300,000,000 actual users.
Then you are going to love IPv6, addressable space of IPv6 consists of....
340,282,366,920,938,463,463,374,607,431,768,211,456 IPs :)
340- undecillion
282- decillion
366- nonillion
920- octillion
938- septillion
463- sextillion
463- quintillion
374- quadrillion
607- trillion
431- billion
768- million
211- thousand
456
Source:
http://elamb.org/2006/12/12/howto-say-the-ipv6-number/