You cannot whitelist it, as this is an action taken on the system level. What you can do is request the IP to be delisted, by visiting the link included in the message (or https://sender.office.com/). Keep in mind however that O365 should not be used to send bulk messages, and you can only request delist few times before getting blocked on a deeper level, without any option to remove the block. If you have a scenario that requires bulk messaging capabilities, either use an on-premises SMTP relay or any of the third-party services that specializes in bulk/marketing email.
Having issue in sending Mail?
Hello experts!
I am using the .onmicrosoft outlook account in EBF Onboarder Tool for sending emails to the users that are migrating.
When I am configuring the Modern Authentication for exchange online mail, and using this account. I am getting the error message and the outlook account is not able to send the email to the users and below is the screenshot of the error:
I have raised this concern to the EBF Support team but they clearly mentioned that this issue is not related to EBF Tool and is because Microsoft is detecting this email as spam by default.
So, How can I whitelist this user account so that I can send mail through this account to the device or users which are migrating through EBF Onboarder Tool?