[Mailman-Users] 4.3.0 mail transport unavailable

Mark Sapiro mark at msapiro.net
Sun Jun 15 05:56:05 CEST 2014

On 06/14/2014 05:04 PM, Stephen J. Turnbull wrote:
> Conrad G T Yoder writes:
>  > I have recently (last couple weeks?) started getting "4.3.0 mail
>  > transport unavailable” bounces from roadrunner/TW addresses (the
>  > rate-limiting issue is not currently rearing its head), and that is
>  > causing Mailman (2.1.17) subscriptions to be disabled.  Example
>  > error message in the “Bounce action notification” email:
> Note that the message you're reporting is a temporary failure (that's
> what a 4.x.x status code means) so I don't really understand why the
> bounce count is being incremented for this.  Whichever MTA is actually
> talking to Time-Warner should be bumping this to a 5.x.x "permanent"
> failure (in this case, giving up after trying repeatedly).

Postfix will keep retrying the temporary failure at intervals until the
message has been in the queue for maximal_queue_lifetime (default 5
days) at which point it gives up and returns the DSN.

The DSN has "Action: failed" which says delivery ultimately failed and
this is what Mailman looks at. The extended status is still 4.x.x which
is the status of each individual (or probably just the last) delivery
attempt. This is compliant with RFC 1893.

RFC 1893 Sec 3.5 says in part:

       X.4.7   Delivery time expired

          The message was considered too old by the rejecting system,
          either because it remained on that host too long or because
          the time-to-live value specified by the sender of the
          message was exceeded. If possible, the code for the actual
          problem found when delivery was attempted should be returned
          rather than this code.  This is useful only as a persistent
          transient error.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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