How other email server (sendmail) will make connection to Exchange 2010 mutli role server.

Question

Hi,
We have 2 Exchange 2010 multi role server and one load balancer for Cas array.
Now we do understand that DAG will be using for database and CAS can be in HA mode via Load balancer.
Now question is, we do have other non-microsoft email server with same smtp address so when this sendmail server will try to make connection to exchange 2010, which server name/ip we need to give them.
Will it be DAG ip/name or do we need to give both server IP.
Amit Rawat | MCITP - Exchange 2007/2010| CCNA |MCSE- 2003| Lync 2010|http://blog.amitrawat.net

Answer 1

you can use whatever Ip's are listening on port 25 on the 2010 hub transports. 
If your load balancer is listening on port 25 and balancing that (probably only a https loadbalancer?) you can use that ip.
If not you can put your 2 cas server IP's in the smart host connector from the sendmail box.
It certainly wont be the DAG ip as the mailbox role has nothing to do with the hub transport.
Foremost i don't have separate CAS here, I do have 2 Exchange(cas/HT/MBX) and DAG is configured.
when sendmail send email to Exchange i need to use some common smtp address to point these servers, so that if one goes down sendmail server can still make connection via that common name.
i can not put two name space(since these 2 exchange are HT server as well) for sendmail server. Any suggestion .
Amit Rawat | MCITP - Exchange 2007/2010| CCNA |MCSE- 2003| Lync 2010|http://blog.amitrawat.net