Re: Getting open smtp servers fixed

[Esa Laitinen <]

On Fri, 11 Sep 1998, Christian Huitema wrote:

> Fixing SMTP servers is very important.  But we should not forget that
> spammers do not actually need to abuse an SMTP relay.  They can simply run
> an SMTP process from their PC, even if that PC only has a dialup
> connection.  The process goes as such:

Quite right, but the spammer did like you suggest, the volume of spam 
he'd get thru before getting axed would be greatly diminished: he would 
have to transmit the e-mail to each mx host, instead of transmitting it a 
few times with huge RCPT TO lists.

Let me see: 2kB e-mail would take about 1 second with 28.8 kbps line, 
about 2 second for session setup (this would be extremely fast). It'd 
take him 3 seconds per message. 20 messages/minute, 1200/hour. 

With open relay, relay having no protections whatsoever (don't know if 
this would work, but an idea anyway): 2kB message 1 second, 2 seconds for 
session setup, 20 chars/address -> 24kB for 1200 addresses (don't know if 
servers accept this much), about 10 seconds for transmitting those. He 
would be able to send 1200 messages in 13 seconds. If this were the case, 
you can calculate how many messages he would be able to send in an hour.

Ofcourse my line of thought might be twisted...  


Esa Laitinen  	             If I cannot reply to your news or mail
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