A client has Exchange 2010 which, up to now, had a single internet connection. They were sending email via a smart host run by their ISP. It was working OK.
We have put in a second internet connection and added a second smart host on the default send connector run by the second ISP.
We have added routing on the firewall so that traffic to Smart Host A goes via the first internet connection and traffic to Smart Host B goes via the second internet connection. When we check the traffic logs, we can see that the server is alternating emails between each smart host and it seems to be running OK.
My question regards delivery failures or bounce backs.
In the past, Smart Host A has randomly rejected emails to certain domains (i.e. hotmail.com). We’ve got round this in by putting the domain in a Direct DNS connector or getting the user to try again.
From now, if Smart Host A, refuses the connection (or rejects an email) for whatever reason, will our Exchange server generate an NDR, or will it try and send the email via the second smart host?
Thanks for your help.
