[Operators] server reputation

Luke -Jr luke at dashjr.org
Fri Apr 18 14:27:55 CDT 2008


On Friday 18 April 2008, Jesse Thompson wrote:
> Luke -Jr wrote:
> > On Friday 18 April 2008, Jesse Thompson wrote:
> >> In the email world, public whitelists aren't all that popular.
> >> Blacklists are.  A server is in effect whitelisted if it isn't on any
> >> blacklist.  I would suggest blacklisting as a first step.
> >
> > I would argue that the DULs are public whitelists since they "list" a
> > large majority of active IP addresses indiscriminately, and are
> > unfortunately quite popular.
>
> "DUL" as in Dynamic Host List?  With some exceptions, it fairly safe to
> block non-authenticated email (and XMPP s2s as an extension) from
> dynamic hosts. 

Maybe if you love to block legitimate emails/IMs.
Most "dynamic" hosts are fairly static.

> I'm not sure why that makes it a whitelist. 

A "static IP" is just an IP that appears on your ISP's "list of static IPs". 
They are not always really static (the subnet may be, but within that subnet, 
they are often DHCP'd randomly), nor are unlisted IPs often really dynamic.
Basically, the distinction between a "static" and "non-static" IP is that 
companies pay to get IP(s) put on a list. A DUL "blacklist" is just an 
inversion of that whitelist.


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