EMail server gets blocked by Microsoft

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.



Have you read this Microsoft guidance on email servers? It covers the most common problems, such as missing SPF records, incorrect or missing IN-ADDR DNS, etc:

-mel beckman

Hi Dominque,

And sign up for snds

It will give you the status of your IPs and you can get jenkmail reports etc.


Hi Dominuque,

If you mean "Microsoft 365" mail servers, your mail server is quite possibly listed frequently on Spamhaus' blocklists.

Check back with Spamhaus on your reputation to find out what you can do.

跡部 靖夫 (ATOBE, Yasuo)

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.

That shit doesn't even work. Just tried. First, you HAVE TO create a Microsoft account to access it. Then, solve some riddles. Enter the IP range you're responsible for. Receive an E-Mail containing a confirmation link which you must click on, and if you do, you get: "Unknown authorization request ID". (Yeah, c&p doesn't work either) And that's it. And you just wasted 5 minutes of your life. So typical.

ProTip: Click "Access Control" on the left hand side of the page after
you get the "Unknown authorization request ID" error. :slight_smile:

-Jim P.

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.

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