In my previous post, one of my complaints was that I had deleted a journal mailbox connector, yet the email kept flowing out the connector to the partner organization.
The problem is that new Exchange Admin Center –> Mail Flows –> Connectors shows you an administration interface that appears to let you administer your connectors. You can create a new connector in the new Exchange Admin Center; but you cannot delete it. Well, the new Exchange Admin Center will show you that it is deleted, but the mail will continue to flow out of your network.
The only way to stop the flow of email out through the connector is to switch to the classic Exchange Admin Center.
Then, when you go in to classic Exchange Admin Center –> Mail Flows –> Connectors you will see that your connector still exists and is pumping out your email.
The particular deliciousness of this failure is that as of the end of last week, classic Exchange Admin Center –> Mail Flows –> Connectors shows only a message that to manage the connectors, you have to switch to new Exchange Admin Center.