550 5.7.511 Access denied, banned sender - 45 users impacted

Question

Hi,

Since this morning, emails sent from our private Exchange server hosted at OVH (ovh.com) cannot send emails anymore to Office 365 (and maybe other Microsoft) recipients.

45 users are impacted since 7 hours.

Wanted to delist our IP address on "https://sender.office.com/" but it seems that the server IP is not blacklisted.

Remote Server returned '550 5.7.511 Access denied, banned sender[xxx.xxx.xxx.xxx]. To request removal from this list please forward this message to ******@messaging.microsoft.com. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653. AS(1410) [VE1EUR03FT056.eop-EUR03.prod.protection.outlook.com]'

Seems that Microsoft made a wrong action and blocked all servers starting with xxx.xxx (cannot list IP here).

Help please!

David

Answer 1

Hi

Thank you for your reply.
The procedure you described had already been executed as mentioned in my post but it didn't solve the issue.
Problem was apparently at another level since the sender.office.com site returned that the IP was not blocked.
Problems is now solved, but I don't have any details on what was exactly the problem.
I have been said that Microsoft made an error and delisted hundreds of servers with IPs starting by xxx.xxx.

Answer 2

Hi @Transauto admin

You could firstly try the steps list here: Use the delist portal to remove yourself from the blocked senders list

1. In a web browser, go to https://sender.office.com
2. Follow the instructions on the page. Ensure that you use the email address to which the error message was sent, and the IP address that is specified in the error message. You can only enter one email address and one IP address per visit.
3. Click Submit.
   The portal sends an email to the email address that you supply. The email will look something like the following:
   
4. Click the confirmation link in the email sent to you by the delisting portal.
   This brings you back to the delist portal.
5. In the delist portal, click Delist IP.
   After the IP address is removed from the blocked senders list, email messages from that IP address will be delivered to recipients who use Microsoft 365. So, make sure you're confident that email sent from that IP address won't be abusive or malicious; otherwise, the IP address might be blocked again.

Or we could also follow the suggestion returned above, *To request removal from this list please forward this message to *****@messaging.microsoft.com.

Check if the steps above are able to solve your issue. If not, we may consider openning a ticket with Microsoft to feedback your situation.

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