Re: minimizing bandwidth taken be spam delivery attempts even when identifiable by "To:" address
On Wednesday 15 February 2006 09:58, Daniel B. wrote:
> What anti-spam method minimizes the network bandwith used by spam
> delivery attempts?
None that have any real precision.
> How hard is it to refuse incoming TCP connections to the SMTP port
> based on DNSBL, using exim4?
That is easy, and I run my own DNSBL instead of trying to figure out exim4's
ACLs in great depth.
> Would refusing connections reduce the
> overall traffic (maybe even causing spammer machines to think I no
> longer run an SMTP server?)?
Yes, it will reduce traffic by rejecting the message before DATA. No, the
spammer won't think you no longer run an SMTP server because that assumes
spammers care about delivery notifications (a fact not in evidence).
> Or do spammer machines usually check
> DNS MX records and would they deliver mail to the backup mail server,
> which would then try to deliver it, using up the same bandwidth?
Well, whatever method you use to filter email should be used on all your
inbound MXs, or you're just defeating your own efforts.
> Is rejecting the message at the RCPT command the best action, or
> is something else better?
Any time during the SMTP connection is a good time.
> NOTE: My main problem here is not spam to valid e-mail addresses--
> it is spam to invalid (non-existent) addresses.
Then you won't see any bandwidth difference.
> This is for a server I run on my own machine so I can define my own
> e-mail aliases (which all forward back up to my ISP's SMTP server
> and my ISP-based e-mail address) so I can avoid giving out my "real"
> e-mail address to everyone and can detect who sells/rents/gives my
> e-mail address (one of the aliases) to others.
Just report spam instead of sweating out how you got it if you want to see a
decrease in spam.
--
Paul Johnson
Email and IM (XMPP & Google Talk): baloo@ursine.ca
Jabber: Because it's time to move forward http://ursine.ca/Ursine:Jabber
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