Echange 2010 : Set-ReceiveConnector Failed

You try to set the FQDN on your DEFAULT* receive connector and you encounter this problem :

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Microsoft Exchange Error
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The following error(s) occurred while saving changes:

Set-ReceiveConnector
Failed
Error:
If the AuthMechanism attribute on a receive connector contains the value ExchangeServer, you must set the FQDN parameter on the receive connector to one of the following values: the FQDN of the transport server "exchange box.*************.***", the NetBIOS name of the transport server "exchange box", or $null.

You have to check Anonymous Users, click OK to return to the console then restart the Microsoft exchange Transport service then apply the FQDN Change.

* The one that starts with DEFAULT is your Internet Connector, this receives e-mail from the outside world