I performed an Exchange 2007 to Exchange 2013 migration. After migrating public folders, my next step was to point our internal servers sending SMTP away from Exchange 2007 to Exchange 2013. When I did that, everything was working except for email addresses outside our organization. I found the article linked below that suggested creating a 2nd connector and setting it to accept any recipient. I did that and everything is working as expected.
http://exchangeserverpro.com/exchange-2013-configure-smtp-relay-connector/
Now though, when those servers send to our internal users, sometimes the mail is being marked as junk. I have the remote network settings of the connector set to 10.0.0.0/8 to cover our internal network.
How can I make the Exchange 2013 server see these internal SMTP servers as internal and mark their messages as safe?