Postfix doesn't have any type of automatic detection of any malfunctioning blacklists, it may be configurable on how long to wait for a response, I'm not sure on that, but no dynamic changing of what is being used, if you think that one though, postfix shouldn't do anything like that. Would tempt people to DOS attack the blacklist to bypass it.
As for the exponential deferral queue options, see: queue_run_delay maximal_backoff_time minimal_backoff_time bounce_queue_lifetime maximal_queue_lifetime On Wed, Oct 1, 2014 at 4:42 PM, Ronald F. Guilmette <r...@tristatelogic.com> wrote: > > In message <3j7sdd1mnszb...@spike.porcupine.org>, > wie...@porcupine.org (Wietse Venema) wrote: > >>Ronald F. Guilmette: >>> >>> In message <542c35a7.3050...@rhsoft.net>, >>> "li...@rhsoft.net" <li...@rhsoft.net> wrote: >>> >>> >Am 01.10.2014 um 19:04 schrieb Ronald F. Guilmette: >>> >> What would happen in such a case? Would inbound e-mail start to >>> >> back up horribly, as Postfix waited for DNS responses that were >>> >> not forthcoming? >>> > >>> >no - no answer is just no answer and mail goes through >>> >>> Yeabut, how sloooooooooly? >> >>See "man 5 resolver" for timeouts, retry counts, etc. > > Thank you. I am aware of the general retry scheme. > > Nominally, I believe that there is one try and three retries, > starting at a five second delay and doubling that for each > successive retry. > > So, 5+10+20+40 = 1.25 minutes, in case the server you are querying > is down. No? > > But clients of a typical resolver library (e.g. Postfix) may > optionally request either more or fewer retries. No? > > So I was asking what Postfix does. > > Also, I was sort-of indirectly asking whether or not Postfix > has any in-built mechanism that might automagically spot > malfunctioning blacklist servers and disable their further > use, you know, in order to prevent inbound stuff from getting > all backed up.
