RBL & greylisting on Ubuntu.com smtp

[Jan Claeys]

Op za, 17-06-2006 te 14:00 +0200, schreef Lionel Dricot:
> Hello Jan,
> 
> > All those blacklists can easily be abused (and _are_ abused), and when
> > that happens, or when an error occurs, a lot of innocent people will be
> > affected.  Blacklists are evil when you use them to block mail.  (You
> > can probably use the better ones to add some amount in a spam scoring
> > system though.)
> 
> Perhaps not the best way. But at least mail are not lost because the
> sender is notified with "you are in the XXX blacklist.

The mail is still "lost" and people have to go through all sorts of
silly loopholes (often involving not really interested third-parties) to
be able to contact you.


> > Greylisting has some problems too (mostly delays), but AFAIK they are
> > smaller than those caused by blacklisting.
> 
> I had doubt about greylisting but I'm really surprised by how good it
> is. In fact, it takes approximately one day to completely forgot
> delays. The first day, mails could be delayed (from 5 minutes to two
> hours. Most of them are received with 1/4h delay at max).
> After the first day, you won't notice any delay anymore, I'm really surprised.

Greylisting can cause mails to get lost too (with some types of server
farm configurations) but AFAIK that's rather uncommon (I never
experienced it or heard any first-hand cases).


> And if you are using Evolution, you can't really rely on the client
> side filtering ;-)

False positives: 0% (after the initial training period)
False negatives: < 1%

Bogofilter seems to be reliable enough for me...


-- 
Jan Claeys