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Re: After a 450, queue or try next MX?

2006-08-30 19:22:29

At 11:01 -0400 on 08/30/2006, Michael Kenny wrote about After a 450, queue or try next MX?:

When I contacted the admin at the recipients domain he asserted that my mail server was misconfigured, and that we should be retying. While I'm not going to say that is not the case, I'm trying to figure out first what it is that should happen here.

And I assert that HIS MX Server#2 is misconfigured. As a MX it should be willing to accept (and pass onto MX#1) any email passed to it (although I'd be willing to allow it to send a "550-Drop Dead - I don't want to talk to you" response AFTER it tries to connect to MX#1 as a test it is up and willing to accept valid email) instead of sending a blow-off reply.

Lets look at the scenario with an inoperative MX#1 (instead of the "Go to MX#2 after MX#1's 45x" scenario). I try MX#1, fail to connect, so follow the MX Chain to MX#2 only to get blown off due to it not being configured as a valid fall-back MX server to MX#1. MX#2 should ALSO issue the 45x (unless as suggested above it can talk to MX#1 and thus assume that it is being tried WITHOUT first trying MX#1 [which is NOT a 100% bullet-proof assumption since the problem triggering a valid fall-back COULD be a connectivity problem between sender ISP and MX#1 while sender ISP can still connect to MX#2 due to using a different path - the whole idea of having separate locations for your MXs]).

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