Re: Should ISP's send bounceback on mail to non-existent address?

Steve Baker wrote:

> On Fri, 1 Jul 2005 23:29:05 -0400, "Uriel Wittenberg"
> <urielw@xxxxxxxxxx> wrote:

>>>> It's inefficient.

>>>Actually, no. It's more efficient to blast blindly that to use any
>>>kind of finesse.

>>Hmm. Maybe you're right, I don't know.

> He's wrong. ISPs do use counter measures.

Those countermeasures are useless.

> For example, Comcast delays
> the SMTP response to an invalid address.

Sendmail has that option. It's useless.

Do you know how modern spamware works? Modern ratware programs can
run tens of thousands of simultaneous sending threads. (Remember, a
ratware program can be designed radically differently from a
legitimate SMTP server, which needs to worry about reliable delivery.)

The fact that the 5,000 threads talking to Comcast's servers are each
delayed by (say) 10 seconds means the entire spam run takes an
extra 10 seconds. Big deal.

> Others *do* do checks on the ratio of valid vs. invalid addresses
> and react. A list of valid addresses at a large domain is valuable.

True. See above. Invalid recipient delays are useless unless they can
somehow detect a coordinated attack, and make a coordinated response.
Given that serious spammers commandeer thousands of compromised PC's to
do their spam runs, recognition of a coordinated attack is extremely
difficuly.

> On one hand Sympatico is protecting their customers, but on the other
> hand they are delivering crippled email service.

I used to be a Sympatico customer. Trust me when I say they're clueless. :-)

Regards,

David.
.

Relevant Pages

  • Re: Im newbie so I might understand more
    ... cal it "invalid syllogism". ... the truth of "an unstable system is useless" unless some connecting link ... what you call invalid syllogism." ...
    (sci.engr.control)
  • Re: TOT: phone for old geezer
    ... >> his current phone (Sony K750) are too small to read, and it's useless ... I assume the LCD display is the type that the more external ambient ... Please replace invalid and invalid with gmx and net to reply. ...
    (uk.tech.digital-tv)
  • Registry Cleaner
    ... High Priority: Value is invalid - Set to Delete ... Cleaner proposing to reset the value to the default? ... And if I wind up not, then the proggy is pretty useless. ...
    (microsoft.public.windowsxp.general)
  • Re: Registry Cleaner
    ... the registry the invalid value can be found. ... Cleaner proposing to reset the value to the default? ... High Priority: Value is invalid - Set to Delete ... And if I wind up not, then the proggy is pretty useless. ...
    (microsoft.public.windowsxp.general)