gpg: failed to create temporary file '/var/lib/lurker/.#lk0x5810e100.hantslug.org.uk.7879': Permission denied
gpg: keyblock resource '/var/lib/lurker/pubring.gpg': Permission denied
gpg: Signature made Wed Apr 25 17:56:45 2007 BST
gpg: using DSA key 2099B64CBF15490B
gpg: Can't check signature: No public key
On Wed, Apr 25, 2007 at 05:40:19PM +0100, Tom Dawes-Gamble wrote:
>
> On Wed, April 25, 2007 3:06 pm, Andy Smith wrote:
> > Just bear in mind it is not a panacea and has some quite serious
> > downsides.
>
> What are these serious downsides?
First and foremost you have to tweak what you consider to be "the
same source" when looking for attempts from "the same source" --
large networks like gmail, yahoo!?!?!, and so on have hundreds of
IPs in several blocks, any of which may later relay the same message
to you. If you do it by single IP it is possible to never see the
same IP in days or weeks, which may not be within the window you
allow for that. Even /24s can introduce significant delay.
Next there is the fact that you cannot dictate the retry schedules
of remote networks, and some providers use extremely annoying ones.
Unfortunately they tend to be the likes of NTL, who are known to not
bother retrying for 24 hours yet can't be written off because they
have a lot of users. Email is not expected to be instant of course,
but if you greylist everything you can sometimes find yourself in
the position of signing up to a web service or the like and then
having to wait hours or days to get your authentication. Irritating
if it's just you; can be fatal to the concept of greylisting if this
is your users or your boss.
Basically you are intentionally slowing down email by rejecting it
temporarily. In an ideal world where everyone complies with common
internet practice this would introduce a ~10 minute delay, once.
However the real world is full of companies like NTL and Yahoo!?!?!
Now consider the fact that the only reason why greylisting works is
that spam drones typically don't implement a queuing strategy to
deal with temporary failures. As more people implement greylisting,
so the drones will start to cope with tempfails; it's not hard. So
the whole idea has a very limited lifespan which reduces faster the
more people use it.
There is still no FUSSP:
http://www.rhyolite.com/anti-spam/you-might-be.html
Cheers,
Andy
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