|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: verizon.net and other email grief
on Fri, Dec 10, 2004 at 12:36:12PM -0800, william(at)elan.net wrote: > On Fri, 10 Dec 2004, Rich Kulawiec wrote: > > > Verizon has put in place an exceedingly stupid "anti-spam" system which > > does not work, which facilitates DoS attacks, and which provides active > > assistance to spammers. > > The technique discussed is called callback verification and I do not > agree that the technique stupid or provides assistance to spammers. > I do agree that some of the aspects in how this was implemented by > Verizon is not correct and causing problems. <snip> > But for current situation it does work just fine and causes number of > emails with randomly generated emails to be stopped. Erm. Yeah, it stops them from being delivered to Verizon by shifting half the cost of verification onto the victims. > >, and (b) it doesn't scale. > > The scalability depends on implementation. Since we have Verizon > implementing it, I'm guessing it scales just fine based on the size > of their email network. See above. It doesn't scale when /everyone else/ starts doing it. > Callback verification if properly implemented will never generate more > junk SMTP traffic as DATA part of SMTP transmission never happens. By the time Verizon's callback servers hang up on us they've already generated more junk SMTP traffic, wasted our resources to protect their customers, and aided spammers doing list validation. Your claim that dictionary attacks are always alphabetical is pretty weak and brings nothing to bear on the actual problem - that by rejecting mail from a given address because of (possibly spurious) "verification", they are actually giving the spammers a tool they can use to cull bad addresses from their own lists. The only positive thing I have to say about Verizon's callback scheme is that so far it has not been seen here more than 6 times in a single day in the past two months. So they must be doing some caching, given that at least one of the domains we host has been under joe job outscatter attack for several months running now. -- hesketh.com/inc. v: +1(919)834-2552 f: +1(919)834-2554 w: http://hesketh.com join us! http://hesketh.com/about/careers/account_manager.html join us!
|