setup 2nd recieve connector on sbs2011

Hi I have an SBS2011 server sending mail using DNS all working
Have a second server 2003 std on the Network that uses a Real-estate program to email customers.
Was OK when using the ISP Smtp , but now they have change to an ISP that doesn’t have one.
& I need to setup a receive connector on the SBS2011 server
I tried a few combinations, but No luck
Question are Authentication & Permission groups to use:



FQDN      Use either or full local address?
Network: I’ve added the IP address of the Server required to send
PORT: Should I change the Port setting & if so to what Port & does it matter
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Authentication
TLS
Enable Domain Security (Mutual Auth TLS)
Basic Authentication & Offer Basic Authentication only after starting TLS
Exchange Server Authentication
Integrated Windows Authentication
Externally Secured (for example, with IPsec)


Permission Groups
Anonymous user
Exchange users
Exchange servers
Legacy Exchange Servers
Partners