Forum Discussion
HOW TO FORCE REMOVE contoso.ONMICROSOFT.COM MAIL ALIAS ?
HI, HOW TO FORCE REMOVE .ONMICROSOFT.COM MAIL ALIAS? the mail that should remain is contoso.com users are synched from local AD. thanks
to prevent external senders to send to .onmicroft.com alias
Makes sense I guess. As mentioned, I seem to recall you cannot really remove these in a hybrid identity situation. You could leave them in place and reject all external email directly sent to the onmicrosoft.com domain as an alternative option. There’s an old article at the link below, not sure if it’s still applicable nowadays but a quick scan through it seems it should be.
https://docs.microsoft.com/en-us/archive/blogs/rrajan/how-to-block-direct-delivery-to-email-address-with-the-suffix-as-domain-onmicrosoft-com-or-domain-mail-onmicrosoft-com
https://docs.microsoft.com/en-us/archive/blogs/rrajan/how-to-block-direct-delivery-to-email-address-with-the-suffix-as-domain-onmicrosoft-com-or-domain-mail-onmicrosoft-com