EMail server gets blocked by Microsoft

Jean St-Laurent jean at
Wed Apr 28 11:59:36 UTC 2021

I just unlocked with this tool for,, and maybe all the O365 suite.


It was fix in less than 24 hours.


Thanks for the tip



From: NANOG < at> On Behalf Of Mike Hammett
Sent: April 28, 2021 7:52 AM
To: Michael Fallen <mikefallensignup at>
Cc: nanog at
Subject: Re: EMail server gets blocked by Microsoft


Neither Microsoft nor Google have been successful at making tools that work for low-volume mailers. They seem to think that if you're not in their club, you're either a commercial email marketing firm or SPAM.

Mike Hammett
 <> Intelligent Computing Solutions
 <>  <>  <>  <> 
 <> Midwest Internet Exchange
 <>  <>  <> 
 <> The Brothers WISP
 <>  <> 


From: "Michael Fallen" <mikefallensignup at>
To: "Dominque Roux" <dominique.roux at>
Cc: nanog at
Sent: Tuesday, April 27, 2021 9:22:29 AM
Subject: Re: EMail server gets blocked by Microsoft

Microsoft seems to be one of the worst offenders in terms of having a 
email blocking blackbox. Good luck getting in contact with someone as 
well. Throughout the years of self-hosting email they have always been 
the most problematic of the large providers.


Dominque Roux wrote on 2021-04-27 3:35 AM:
> Hi All,
> is there anyone out there who has some experience with the blocking
> mechanism of Microsofts mail server? We're running a mail server at our
> company which ends up on their blacklist from time to time and we're
> wondering if there are some steps we could take in order to prevent this.
> Cheers,
> Dominique


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