Since 22 December we have not been able to send email to Office365 email addresses - we get a message that our server is banned:

For example:

<aaa@sample.com.au>: host
    sample.mail.protection.outlook.com[] said: 550
    5.7.511 Access denied, banned sender[xxx.xxx.xxx.xxx]. To request removal
    from this list please forward this message to
    delist@messaging.microsoft.com. For more information please go to
    http://go.microsoft.com/fwlink/?LinkId=526653. AS(1410)
    [SY4AUS01FT011.eop-AUS01.prod.protection.outlook.com] (in reply to RCPT TO command)

email address and our server ip removed for privacy

I have emailed delist@messaging.microsoft.com and followed all the steps, but the problem remains.

It seems others have had the same problem since 22 December: https://techcommunity.microsoft.com/t5/office-365/trying-to-find-help-for-550-5-7-511-access-denied-banned-sender/m-p/3046157#M37128

Can anyone shed any light on this, and how to get it resolved?

  • The way to get this resolved is not to run your own mail server. Sorry. E-Mail is a closed community nowadays.
    – Daniel B
    Dec 27, 2021 at 9:34
  • Seems to be related to Linode IP address range from what I can tell, or at least a LOT of people on Linode are complaining about this. MS is just ignoring it AFAICT
    – pmc
    Dec 31, 2021 at 0:25
  • You are correct. Microsoft have advised their servers currenly will not accept email from any Linode IP addresses....
    – ausadmin
    Jan 1 at 2:15
  • For f**s sake, I'm also a Linode customer and affected by this problem. It's mind-boggling hard resp. impossible to get a delisting. Running my own mail server since 2001. The effort required increases from year to year.
    – weeheavy
    Jan 20 at 21:13
  • 1
    @weeheavy I dont have any specific contact information. I basicall followed the advice in the answer post, but I did not have to set up a trial account as we already had a MAPS subscription which included Office365. After some very frustrating correspondence with front line support over a week, I finally got it escallated, and it was someone from Microsoft 365 Escalations that finally got our IP address added to the whitelist.
    – ausadmin
    Jan 27 at 21:02

1 Answer 1


Try setting up an O365 trial account http://www.microsoft.com/en-us/microsoft-365/enterprise/e3 and try submitting a ticket there, then do your best to get through lvl1 and lvl2 nonsense and you should be able to make them escalate it internally and do something.

I would take it as a best bet although it might take more than a single ticket :(

  • Great suggestion, thanks I have done this, but right now I am having trouble getting them to escalate the issue. Its really hard because I cant even email support (it just bounces because of this problem), so I have to rely on their engineer calling me, and they are in the opposite time zone.
    – ausadmin
    Dec 30, 2021 at 10:20

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