On the Restricted users page, find and select the user that you want to unblock by clicking on the user. To go directly to the Restricted users page, use. In the Microsoft 365 Defender portal at, go to Email & collaboration > Review > Restricted users. Use the Microsoft 365 Defender portal to remove a user from the Restricted users list For more information, see Responding to a compromised email account in Office 365. Before you remove the user from the Restricted users portal, be sure to follow the required steps to regain control of their account. The View-Only Organization Management role group in Exchange Online also gives read-only access to the feature.Ī sender exceeding the outbound email limits is an indicator of a compromised account. For more information, see About admin roles.
"Your message couldn't be delivered because you weren't recognized as a valid sender.
When they try to send email, the message is returned in a non-delivery report (also known as an NDR or bounce messages) with the error code 5.1.8 and the following text: The user is added to the Restricted users page in the Microsoft 365 Defender portal. If a user exceeds one of the outbound sending limits as specified in the service limits or in outbound spam policies, the user is restricted from sending email, but they can still receive email.
This new experience brings Defender for Endpoint, Defender for Office 365, Microsoft 365 Defender, and more into the Microsoft 365 Defender portal. The improved Microsoft 365 Defender portal is now available.