You can't add a specific domain name for the address space if the Send connector has a "-" value specified as the address ...

You can't add a specific domain name for the address space if the Send connector has a "--" value specified as the address space. This Send connector is managed by the Microsoft Exchange EdgeSync service to deliver inbound e-mail, and the value "--" refers to all accepted domains for the Exchange organization. Please refer to the EdgeSync documentation before you modify the address space values.