Hi! May i have some recommendations for my Exchange Server 2007? 1. Is it ok to have one Public IP for 3 Internet Domains from where we want to receive and send e-mails to? We have only one Exchange Server. Or it is better to have 3 different public ips for these domains. Can exchange be configured for 3 different external e-mail domains having 3 different public ips? Our Internal domain name is different from external domain names. 2. What is the best (Expensive) and (the Cheapest) solution if we need to keep our Internal Exchange Server synchronized with an External Web Based E-Mail Service so that if our Internal Exchange Server goes down our E-Mail users can still connect to their mailboxes through web? Thanks.

There is no point having multiple IP addresses for each domain. Just use the same IP address, same MX record host for all three. All traffic will go out on the same IP address anyway, so will need to have a correct DNS record. You cannot make the server route traffic out of different IP addresses depending on the sending domain. If you moved to Exchange 2010 then you could use a DAG to a server in a data centre. Very few other solutions because of the problem of getting email delivered. Google have launched something, but you still have the issue of where email is delivered to during an outage. If you stick with Exchange then you can have email delivered to any server in the Exchange org. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources