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: -
NetName: MSFT

A bit of an oversight?


Which "Exchange tools site" are you referring to?

Happy to help get this fixed up.



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


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.



NetRange: -
NetName: MSFT
NetHandle: NET-13-64-0-0-1
Parent: NET13 (NET-13-0-0-0-0)
NetType: Direct Assignment
Organization: Microsoft Corporation (MSFT)
RegDate: 2015-03-26
Updated: 2015-03-26

OrgName: Microsoft Corporation
Address: One Microsoft Way
City: Redmond
StateProv: WA
PostalCode: 98052
Country: US
RegDate: 1998-07-09
Updated: 2017-01-28

Comment: For routing, peering or DNS issues, please
Comment: contact:
Comment: *

It's one of the outbound IP addresses for the Microsoft Remote Connectivity
Analyzer, as documented here:

Your client's mail exchanger is rejecting the test e-mail message because
that particular outbound IP address does not have PTR resource record.
Interestingly, all of the IP addresses listed do not.

Josh should reverse to |

*Optional:* Remote Connectivity Analyzer
<; - Initiate connectivity tests.




TCP 80 & 443


Hah. Thanks. :slight_smile:

Yes, it's a big shop..

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.