On Fri, 2011-06-10 at 10:08 +0200, Robert Schetterer wrote:

Hi , just to make clear short question does auth_cache... help with downing sql lookups http://wiki2.dovecot.org/Authentication/Caching

Sure, that's what it was built for.

isnt clear to me for sql to me if yes are there real world recommanded settings lets say for a 5000 users server and where password changes should be noticed asap

If you want to be absolutely sure that password changes are noticed immediately, disable negative caching.