Querying other SMTP server for valid addresses?

[Steve Swaney]

> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
> Behalf Of Mike Bacher
> Sent: Friday, November 19, 2004 7:20 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: Querying other SMTP server for valid addresses?
>
> Steve Swaney wrote:
>
> > A bit more sophisticated but the answer is essentially yes.
>
> My only concern would be performance.  Yes, I know it caches (as does
> exim) but with the
> huge amount of dictionary attacks that many of us see each day it might be
> a problem
> performance wise.  We currently do LDAP lookups which work OK, but it has
> some downsides
> related to domain aliases on our primary mailhost.

I've had some correspondence with the author, Anthony C Howe, and some
limited experience just watching logs scroll by :) Anthony thinks the
rejection of most dictionary attacks leads to overall improved performance
on the email gateway. I agree, although I don't yet have any empirical
evidence.

I also had an earlier post today that discussed performance issues

The time it takes to make the query appears to be very quick for most of the
domains we are testing - and they are not local domains.

Steve

Steve Swaney
President
Fortress Systems Ltd.
www.fsl.com
steve.swaney at fsl.com
>
> -----------------------------------------
> Mike Bacher / isp-list at tulsaconnect.com
> TCIS - TulsaConnect Internet Services
> Phone: 918-584-1100x110 Fax: 918-582-5776
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This message has been scanned for viruses and
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believed to be clean.

Fortress Systems Ltd.
www.fsl.com

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