On Tue, 31 Jul 2001, Dean Brooks wrote:
> Imagine a situation where AOL or some other large ISP gets
> (accidentily) listed in the RBL lists and then gets quickly removed
> when the mistake is found. With short TTLs, DNS will get the updates
> quickly but Exim would still have this data cached for some unknown
> amount of time.
Not really. Remember Exim operates with short-lived processes. Any
feasibly implemented caching would apply to a single incoming message
only. This is implemented in Exim 4 so that you can write ACL rules of
the following general meaning (this is NOT the actual syntax!):
if authenticated and RBL lookup then warn
else if RBL lookup then deny
If the lookups are the same, only one will be done. This is very
limited, per-process caching. "Serious" caching is left to the resolver
and/or name server.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
