Re: [Exim] Dealing with spam from outblaze.com

On Wed, 22 Jan 2003, Suresh Ramasubramanian wrote:

> Try spamassasin or something (or maybe open proxy dnsbls) rather than
> sender verify callouts - I would rather not have further unnecessary
> connections to our MXs at the moment, thankyouverymuch.

Speaking for ourselves, we try as far as possible to perform low-cost
checks first, working up to high-cost ones last: that means testing
local blacklists first, then the DNS-based RBLs, and only if the mail
gets past those, and then only if the sender domain is in our list of
domains for which we've concluded that callbacks are a worthwhile
exercise, do we actually try that.

The results of these callbacks need to be cached, though, since I have
the impression that spammers often repeat the same counterfeit sender
for a while before switching to a using a different one.