Does Microsoft Exchange retry delivery correctly?

Gary Mills
Fri Oct 6 13:59:51 UTC 2006

On Sat, Sep 16, 2006 at 09:17:04AM -0500, Gary Mills wrote:
> Has anyone else noticed problems with Microsoft Exchange and DCC
> greylisting?  Until recently, I've been telling people that Exchange
> does follow the SMTP standards correctly.  Lately however, I've seen
> a couple of instances where Exchange never retried delivery after
> a 452 response from our MTA.
> One such server identified itself as `Microsoft ESMTP MAIL Service,
> Version: 6.0.3790.1830' in its SMTP banner, and as `Microsoft Exchange
> V6.5' in the e-mail headers.  Is this a recent version?  I'm wondering
> if a recent change broke the retries.  Does anyone know of a patch or
> a configuration option that corrects this behavior?

I have some new information on this problem, thanks to a nearby
Exchange site that was having problem sending e-mail to us.  Our
sendmail logs showed that Exchange never retried delivery after a
temporary delivery failure code.  The admin restarted the Exchange
service and tested with a fresh sender/recipient pair.  This time, it
retried very nicely, first one minute apart and then ten minutes
apart.  This was with Exchange 5.0.2195.6713, according to their SMTP
banner.  So, it does work most of the time.

-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-

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