MSFT reverse IP failure?

Jeff Mealiffe jeffmeal at
Wed Feb 28 21:11:42 UTC 2018

I've escalated this to the team responsible for the tool. Will report back when we have some resolution.

Thanks for calling out the issue.

-----Original Message-----
From: NANOG <nanog-bounces at> On Behalf Of Ken Chase
Sent: Monday, February 26, 2018 4:05 PM
To: Christian Kuhtz <chkuhtz at>
Cc: nanog at
Subject: Re: MSFT reverse IP failure?

Im not exactly sure what this is either, the client sent me a screenshot that called itself the "microsoft connectivity analyzer", which had several steps testing deliverability of email to their domain, with the final test of an actual test email delivery failing.


On Mon, Feb 26, 2018 at 11:25:59PM +0000, Christian Kuhtz said:
  >A little difficult to say what this without knowing what actually is.   If this is an Azure deployment, ReverseFqdn needs to be populated on the Public IP address resource.  Please take a look here
  >-----Original Message-----
  >From: NANOG <nanog-bounces at> On Behalf Of Ken Chase
  >Sent: Monday, February 26, 2018 1:31 PM
  >To: nanog at
  >Subject: Re: MSFT reverse IP failure?
  >Having a client doing a test from the MSFT exchange tools site, which is failing.
  >NOQUEUE: reject: RCPT from unknown[]: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [];
  >NetRange: -
  >CIDR: ,,
  >NetName:        MSFT
  >A bit of an oversight?
  >Ken Chase - math at Guelph Canada

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