Re: Possible MX Lookup/Ordering Issue

From: Wietse Venema (no email)
Date: Thu Nov 01 2007 - 12:25:13 EDT

  • Next message: Ward, Martin: "RE: Debugging .forward-* files - Fixed"

    > On Thu, 1 Nov 2007, Wietse Venema wrote:
    > > :
    > >> Sure - and I've gone one better and hidden my real MX somewhere between
    > >> the rejecting ones at the top (which leads to immediate retries to the
    > >> next MX down, which may or may not do the same thing), and the tarpitting
    > >> ones at the bottom. And even if a valid MTA gets to the bottom ones
    > >> through a minor network outage, it'll still eventually time out and roll
    > >> over to retry from the top after a little while.
    > >
    > > The RFC does not require that an SMTP client tries every MX host.
    > > It only requires two. If you list lots of non-responding MX hosts
    > > then you can expect interoperability problems.
    > Sure - but if the top two were tried in the correct order, this problem
    > wouldn't have happened, and if I saw it give up after two, I'd not be
    > asking why it started at the 16th and didn't go from there for 5 hours.

    What's the TTL in the SOA record for the domain in question?


  • Next message: Ward, Martin: "RE: Debugging .forward-* files - Fixed"

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