Exchange Server 2013 Preview: Anonymous permissions behaviour on Default Frontend Receive Connector
Hello folks,
You may have notice that Exchange Server 2013 has additional Receive Connectors to support the new architecture and we are going over them in a near future post however in Today’s post I would like to show you a small but still interesting improvement on the receive connector listening on 25 port.
By default on Exchange Server 2007/2010 wasn’t able to receive Internet traffic however in Exchange Server 2013 the connector responsible for 25 has the Anonymous checked as standard value which means that any relay to an accepted domain will be received without any additional configuration.
In order to check it out, open EAC (Exchange Admin Center), click on Mail Flow and then Receive Connectors and double click on Default frontend <servername>
Here we go.. the Anonymous is selected and you can relay right away messages on that connector. Cool, isn’t it? 
Cheers,
Anderson Patricio
http://www.andersonpatricio.ca
http://www.andersonpatricio.org (Portuguese)
Twitter: @apatricio