Emails from O365 are not being forwarded to InstanceIssue You may see this issue if you have an email address in your O365 which you have configured to forward to your instance. An additional symptom is that the message will be returned to the sender win an NDR that contains the following information 5.7.520 Access denied, Your organization does not allow external forwarding. Please contact your administrator for further assistance. AS(7555)ReleaseAnyCauseThis is caused by an outbound spam filter on your O365 Mail server Resolutionhttps://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/external-email-forwarding?view=o365-worldwide Contains more information and details on how to configure O365 to resolve this