On Tue, 05 Nov 2002 13:57:25 CST, "John W. Luther" <[log in to unmask]>  said:

> 1 11/04 11/04 [log in to unmask]
> Last error: Unavailable; DSN status was 5.1.1
>
> The list owners are now asking if the mail that failed to be delivered will be resent by Listserv.  I've been looking at Listserv Site Manager and Developer manuals, but am not finding this issue addressed (yet).  My thought is that Listserv makes one attempt to hand the mail off to the mail system and is then done with it, that no continuing attempts will be made to send from Listserv to the affected mail addresses.  In other words, the Listserv will not re attempt to send that particular message to the offending mail addresses.  Am I correct in this inference?

The RFCs specifically state that 4xx errors and 4.n.n DSN codes are retryable
(as they should be used for timeouts, out of resources temporarily, etc),
for conditions that are likely to resolve themselves without human intervention.
A 5xx error or 5.n.n DSN code is to *NOT* be retried without a human taking
a look and deciding whether to retry.

The case could be made that Exchange should have issued a 4xx error when it
realized it had a hardware issue, so mail would sit on the sending system's
queue.  Of course, there exist points in the process where it's really
hard for it to "know" that it's got a problem (if a hardware fault kills
a process outright, a "5xx and yell for help" may be the only realistic option).
--
                                Valdis Kletnieks
                                Computer Systems Senior Engineer
                                Virginia Tech