Hi Sam. It's ridiculous. I'm not a native english speaker, perhaps this is the reason that you are not willing to understand the key point.
Am Mittwoch, 9. März 2011, um 00:12:49 schrieb Sam Varshavchik: > Bernd Wurst writes: > > in this case, is blocked via greylisting by the recipient. > With greylisting, a connection to the server gets successfully established, > but, from the sender's perspective, the delivery attempt fails. Perfect. This is right for the FIRST ATTEMPT. Greylisting is only an example for any reason why the very first attempt fails. > The reasons for the delivery failures are irrelevant. To attempt to > immediately try some other server to deliver the unwanted mail, is > considered to be, at least rude, if not abusive. Rather, it is expected > that the sender would wait, and try again later. That's a perfect strategy. But this second try is never ever done via IPv4 again. > Any attempt to use another IP address, being IPv4 or IPv6, only occurs if > there was a failure to establish a TCP connection. That is not true. When a network problem ocures with IPv6 (routing error), no TCP connection could be established. Courier just gives up and does not try IPv4. That's what I'm trying to say. Imagine the following: IPv4 is fully working. IPv6 has a routing problem. (Our server sent out messages to other servers via IPv4 and the recipient received other messages dunring this log file period.) This is the log (shortened the lines for readability): Mar 6 23:11:00: <...@ak-online.be>: 451-178.63.68.96 is not yet authorized to deliver mail from Mar 6 23:11:00: <...@ak-online.be>: 451 <...> to <...@ak-online.be>. Please try later. Mar 6 23:11:00: <...@ak-online.be>,status: deferred Mar 6 23:16:42: <...@ak-online.be>: Connection timed out Mar 6 23:16:42: <...@ak-online.be>,status: deferred Mar 6 23:45:22: <...@ak-online.be>: Connection timed out Mar 6 23:45:22: <...@ak-online.be>,status: deferred Mar 6 23:51:04: <...@ak-online.be>: Connection timed out Mar 6 23:51:04: <...@ak-online.be>,status: deferred Mar 6 23:56:46: <...@ak-online.be>: Connection timed out Mar 6 23:56:46: <...@ak-online.be>,status: deferred Mar 7 01:17:25: <...@ak-online.be>: Connection timed out Mar 7 01:17:25: <...@ak-online.be>,status: deferred Mar 7 01:23:07: <...@ak-online.be>: Connection timed out Mar 7 01:23:07: <...@ak-online.be>,status: deferred Mar 7 01:28:49: <...@ak-online.be>: Connection timed out Mar 7 01:28:49: <...@ak-online.be>,status: deferred Mar 7 01:57:28: <...@ak-online.be>: Connection timed out Mar 7 01:57:28: <...@ak-online.be>,status: deferred Mar 7 02:03:10: <...@ak-online.be>: Connection timed out Mar 7 02:03:10: <...@ak-online.be>,status: deferred First try CAN establish a TCP connection and then is blocked by greylisting. All further tries run into a timeout because IPv6 is broken. There is no further try on the IPv4 address. The recipient got all mail from us delivered as soon as the IPv6 routing problem was fixed ~36 hours later. > > This problem comes up when a connection via IPv6 should be possible but > > something is broken. This could happen, but that's what fallbacks and > > backup MXes are for. I just think Courier should try all possible > > addresses. > It does. If the TCP connection fails on the network level. Then, what goes wrong regarding my logs above? Bernd -- Ich habe ja auch nie bezweifelt, daß emacs ein tolles Betriebssystem ist. Aber um mit Linux oder Windows konkurrieren zu können, fehlt ihm ein vernünftiger Editor. - Kai Fett
signature.asc
Description: This is a digitally signed message part.
------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d
_______________________________________________ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
