Hi @相 王,
Since this is a public forum, I have covered the personal information in your post for security.
Please do not forget to hide your personal information when posting.
According to your description, please note that it is the expected behavior that Anonymous users should be enabled on the Default Frontend <server_name> receive connector.
Because this connector (listens on port 25) is used to receive inbound messages sent from external senders (to Exchange these external senders are all Anonymous users).
If you disable Anonymous users on this connector, senders sending to your Exchange server will first need to authenticate (in other words only internal users can authenticate), which is not possible so the external messages will be rejected with the error Client was not authenticated to send anonymous mail.
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